GCSE Mathematics - Pearson Edexcel - COMPLETED Flashcards
FLASHCARDS MADE MYSELF WITH AID OF SOURCE BOOK: GCSE (9-1) MATHEMATICS REVISION GUIDE HIGHER BY PEARSON EDEXCEL
What are the factors of a number?
The factors of a number are any numbers that divide into it exactly
How many factors does a prime number have?
A prime number has only 2 factors (1 and itself)
List the prime numbers up to 20:
2, 3, 5, 7, 11, 13, 17, 19
What is a prime factor?
A number is a prime factor if it is both prime and a factor of another number (REMEMBER PRIME FACTORISATION TREES - THE NUMBERS WHICH YOU CIRCLE)
How can you find prime factors?
Using a prime factorisation tree (also known as a prime factor tree)
Let’s say that you just used a prime factor tree to find the prime factors of 84. They are 2, 2, 3 and 7. How would you write 84 as a product of its prime factors in the answer box?
2^2 X 3 X 7
What does HCF stand for?
Highest Common Factor
What is the HCF of 2 numbers?
The highest common factor of 2 numbers is the highest number that is a factor of both numbers
What does LCM stand for?
Lowest Common Multiple
What is the LCM of 2 numbers?
The lowest common multiple of 2 numbers is the lowest number that is a multiple of both numbers
What do indices include (as a category)?
Square roots, cube roots and powers
List the 3 laws of indices:
- x^a X x^b = x^a + b
- x^a / x^b = x^a - b
- (x^a)^b = x^ab
True or false: The cube root of a positive number is always positive, and the cube root of a negative number is always negative
True. The cube root of a positive number is always positive, and the cube root of a negative number is always negative
x^0 =
1 - Anything raised to the power of 0 is equal to 1
x^1 =
x - Anything raised to the power of 1 is equal to itself
List the square numbers up to 15^2:
1 X 1 = 1
2 X 2 = 4
3 X 3 = 9
4 X 4 = 16
5 X 5 = 25
6 X 6 = 36
7 X 7 = 49
8 X 8 = 64
9 X 9 = 81
10 X 10 = 100
11 X 11 = 121
12 X 12 = 144
13 X 13 = 169
14 X 14 = 196
15 X 15 = 225
List the cube numbers of 1, 2, 3, 4, 5 and 10:
1 X 1 X 1 = 1
2 X 2 X 2 = 8
3 X 3 X 3 = 27
4 X 4 X 4 = 64
5 X 5 X 5 = 125
10 X 10 X 10 = 1000
True or False: A negative power always has a negative answer
False. A negative power can still have a positive answer
What is the index law for negative powers?
x^-y = 1 / y^2
What is the index law for powers of fractions?
(x / y)^n = x^n / y^n
What is the index law for reciprocals?
x^-1 = 1 / x. This means that x^-1 is the reciprocal of x. You can find the reciprocal of a fraction by “turning it upside down” - switching the numerator and denominator
What do fractional powers represent?
Roots. For example, x^1/2 = the square root of x (49^1/2 = 7). Or, x^1/3 = the cube root of x (27^1/3 = 3). Or, x^1/4 = the 4th root of x (16^1/4 = 2)
What always happens if we raise a whole number to a power less than one (a fractional power)?
It gets smaller
If the number on the right is 5 or more, we round…
Up
If the number on the right is less than 5, we round…
Down
True or false: When rounding significant figures, the leading zeros in decimals are included
False. Leading zeros in decimals are not counted as significant
Explain the steps you would go through to add or subtract fractions:
- Add or subtract the whole numbers
- Write the fractions as fractions with the same denominator
- Add or subtract the fractions
- If you have an improper fraction then convert to a mixed number and add/subtract
Explain the steps you would go through to divide fractions:
- Convert any mixed numbers to improper fractions
- Turn the second fraction “upside down” - switch the numerator and denominator - and change the / to a X
- Multiply the numerators and multiply the denominators, cancelling where possible
- Convert any improper fractions to mixed numbers
Explain the steps you would go through to multiply fractions:
- Convert any mixed numbers to improper fractions
- Multiply the numerators and multiply the denominators, cancelling where possible
- Convert any improper fractions to mixed numbers
What are terminating decimals?
Decimals which can be written exactly. They can be written as a fraction with the denominator 10, 100, 1000 and so on
What are recurring decimals?
Decimals that have one digit or group of digits repeated forever. You can use dots above the numbers to show the recurring digit (single dot above the digit) or recurring group of digits (two dots on the first and last digits of the group)
How would you check if a fraction will produce a terminating or a recurring decimal?
Write the fraction in its simplest form, then find the prim factors of the denominator. If the prime factors are only 2 and 5 it is a terminating decimal. If the prime factors are other than just these it is a recurring decimal
How can you estimate the answer to a calculation?
Round each number to 1 significant figure and carry out the calculation with these numbers
What does ≈ mean?
Approximately equal to
Explain the steps you would go through to convert a recurring decimal into a fraction:
- Write the recurring decimal as n
- Multiply by 10, 100, 1000 (depending on the number of recurring digits)
- Subtract to remove the recurring part
- Divide by 9, 99 or 999 to write as a fraction (depending on the number of recurring digits)
- Simplify the fraction
What are upper and lower bounds a measure of?
Accuracy
To find the overall upper bound of a + b, we use the equation…?
Overall upper bound of a + b = upper bound of a + upper bound of b
To find the overall lower bound of a + b, we use the equation…?
Overall lower bound of a + b = lower bound of a + lower bound of b
To find the overall upper bound of a - b, we use the equation…?
Overall upper bound of a - b = upper bound of a - lower bound of b
To find the overall lower bound of a - b, we use the equation…?
Overall lower bound of a - b = lower bound of a - upper bound of b
To find the overall upper bound of a X b, we use the equation…?
Overall upper bound of a X b = upper bound of a X upper bound of b
To find the overall lower bound of a X b, we use the equation…?
Overall lower bound of a X b = lower bound of a X lower bound of b
To find the overall upper bound of a / b, we use the equation…?
Overall upper bound of a / b = upper bound of a / lower bound of b
To find the overall lower bound of a / b, we use the equation…?
Overall lower bound of a / b = lower bound of a / upper bound of b
What are the 2 most important rules to remember when dealing with surds?
Square root of ab = square root of a X square root of b
AND
Square root of a/b = square root of a / square root of b
What are you being asked to do if a surds question asks you to rationalise the denominator?
Make the denominator a whole number. You can do this by multiplying the top and bottom of the fraction by the surd part of the denominator
How would you count possibilities using calculation?
Multiply the number of choices for each option. For example:
I have a 4 letter password I am trying to guess: p7m$
The first character must be a letter - 26 possibilities
The second character must be a digit 0 - 9 - 10 possibilities
The third character must be a letter - 26 possibilities
The fourth character must be one of $, *, _ or # - 4 possibilities
So the total number of possibilities for my password is 26 X 10 X 26 X 4 = 27,040 possible combinations
How many sets of brackets will you need to factorise the expression x^2 + bx + c?
2 brackets
When factorising x^2 + bx + c, when will both factors be positive?
When b and c are both positive
When factorising x^2 + bx + c, when will the larger factor be positive and the smaller number be negative?
When b is positive and c is negative
When factorising x^2 + bx + c, when will the larger factor be negative and the smaller factor be positive?
When b and c are both negative
When factorising x^2 + bx + c, when will both factors be negative?
When b is negative and c is positive
What is factorising (and what do you need to look for)?
Factorising is the opposite of expanding brackets. You look for the largest factor you can take out of every term in the expression
How would you factorise the expression (something)^2 - (something else)^2 - WHAT FORMULA WOULD YOU USE?
a^2 - b^2 = (a + b)(a - b)
EXAMPLE:
x^2 - 36 = x^2 - (6)^2
= (x + 6)(x - 6)
When factorising x^2 + bx + c, you are looking for 2 numbers which…?
SUM to b and MULTIPLY to make c
What is a formula?
A mathematical rule
What is the plural form of formula?
Formulae
What does BIDMAS stand for?
Brackets
Indices
Division
Multiplication
Addition
Subtraction
What is an arithmetic (also known as a linear) sequence?
A sequence of numbers where the difference between the consecutive terms is constant
Explain the steps you would take to find the nth term of a linear sequence:
- Write in the difference between each consecutive term in the sequence
- Work backwards to find the zero term in each sequence (ie. if the sequence starts with 1 and the difference between all the following numbers is 4, -4 from one to find the zero term is -3)
- Write down the nth term - remember nth term = difference X n + zero term
What is the formula for the nth term?
nth term = difference X n + zero term
What is the rule for a Fibonacci sequence?
The rule for generating a Fibonacci sequence is ‘add two consecutive terms to get the next term’. EXAMPLE: 2, 3, 5, 8, 13, 21…
What is a quadratic sequence?
A sequence where the nth term contains an n^2 term (and no higher power of n)
You can also write the nth term in shorthand as…
u↓n
You can write the rule for the nth term of a quadratic sequence in shorthand as…
u↓n = an^2 + bn + c where a, b and c are numbers and a is not 0
True or false: The second differences in quadratic sequences are constant
True. EXAMPLE:
SEQUENCE: 2, 10, 24, 44, 70, 102
1ST DIFF: +8, +14, +20, +26, +32
2ND DIFF: +6, +6, +6, +6
So the second differences in quadratic sequences are constant
Explain how you would find the nth term of a quadratic sequence:
- Write out the first set of differences between each consecutive value in the sequence - NOT CONSTANT
- Next write out the differences between the first set of differences - THIS SHOULD BE CONSTANT - THIS IS THE NUMBER YOU CARRY FORWARD
- The coefficient of n^2 in the nth term is always half the second difference, so halve your number to find the value of a
- Draw out a table to compare the values of n (1 counting up) and the nth term (your sequence in order)
- You now know the value of a - add another row for an^2 and multiply a by each number for n
- Subtract this new sequence from each term in your original sequence to form an arithmetic sequence with a constant difference
- The nth term of your arithmetic sequence is the second half of the nth term of your quadratic sequence (ie. if a was 0.5^2 and the arithmetic sequence had an nth term of 0.5n, your overall expression is 0.5^2 + 0.5n)
If an equation is in the form y = mx + c, its graph will be a ……….. line
If an equation is in the form y = mx + c, its graph will be a straight line
In the equation y = mx + c, what does the m tell you?
The gradient
In the equation y = mx + c, what does the c tell you?
The y-intercept (at what y-coordinate the line intersects with the y-axis)
How would you go about plotting a straight line graph?
Draw a table of values for x and y, use substitution to figure out the values and plot the (x, y) coordinates on the graph - they should form a straight line graph
What is the equation for calculating gradient (m)?
m = y^2 - y^1 / x^2 - x^1
Explain how you would find the equation of a straight line graph given one point and the gradient:
- Substitute the gradient for m into y = mx + c
- Substitute the x and y values given in the equation (for y and x respectively)
- Solve the equation to find c
- Write out the finished equation
Explain how you would find the equation of a straight line graph given 2 points:
- Draw a sketch showing the 2 points
- Work out the gradient of the line by drawing a triangle
- Now that you know the gradient and at least one of the points you can use the other method.
- Substitute m into the form y = mx + c
- Choosing one of the (x,y) points you have, substitute this into the equation y = mx + c
- Solve the equation to find c
- Write out the finished equation
If the line slopes down, the gradient is…
Negative
True or false: Parallel lines have the same gradient
True. Parallel lines have the same gradient
If the line sloped up, the gradient is…
Positive
What does perpendicular mean?
At right angles
If a line has gradient m then any line perpendicular to it will have gradient of:
- 1 / m
What is a line segment?
A short section of a straight line
What contextual information will you need to know in order to find the midpoint of a line segment?
The coordinates of each end of the segment
What is the equation for finding the coordinates of the midpoint of a line?
Coordinates of midpoint = (average of x-coordinates, average of y-coordinates)
What type of graphs do quadratic equations have?
Curved graphs
What is the turning point of a graph?
The point where the direction of the curve changes
What are cubic graphs?
Graphs that contain an x^3 term and no higher powers
What are reciprocal graphs?
Graphs of the form y = k / x where k is a number
What does a distance-time graph show?
How distance changes with time
What does a horizontal line on a distance-time graph mean?
A horizontal line means no movement
What do straight lines on distance-time graphs mean?
That the subject was travelling at a constant speed
What does the gradient of a distance-time graph tell you?
The rate of change of distance with time (THIS IS ALSO CALLED SPEED)
What form are quadratic equations written in?
ax^2 + bx + c where a, b and c are numbers
Explain how you would solve a quadratic equation:
- Rearrange into the form ax^2 + bx + c
- Factorise the left hand side
- Set each factor equal to zero and solve to find 2 values of x
What is the quadratic formula?
The solutions of the quadratic equation ax^2 + bx + c = 0 where a != o are given by:
x = -b +- square root of (b^2 - 4ac) / (2a)
How many solutions can a quadratic equation have?
A quadratic equation can have 2 solutions, 1 solution or no solutions
For quadratic equations in the form ax^2 + bx + c, if b^2 - 4ac is negative how many solutions are there?
No solutions - you cannot calculate the square root of a negative number
For quadratic equations in the form ax^2 + bx + c, if b^2 - 4ac is equal to zero how many solutions are there?
One solution
For quadratic equations in the form ax^2 + bx + c, if b^2 - 4ac is greater than zero how many solutions are there?
Two different solutions
What is the equation for completed square form?
If a quadratic expression is written in the form (x + p)^2 + q it is in completed square form - YOU CAN SOLVE QUADRATIC EQUATIONS WHICH DON’T HAVE INTEGER ANSWERS BY COMPLETING THE SQUARE
What are the 2 identities which you can use to save time when you are completing the square?
- x^2 + 2bx + c ≡ (x + b)^2 - b^2 + c
- x^2 - 2bx + c ≡ (x - b)^2 - b^2 + c
Explain the algebraic solution steps for solving simultaneous equations:
- Number each equation
- If necessary, multiply the equations so that the coefficients of one unknown are the same
- Add or subtract the equations to eliminate that unknown
- Once one unknown is found use substitution to find the other
- Check the answer by substituting both values into the other equation
When graphing simultaneous equations, the coordinates of the point of intersection tell you what?
The solution to the simultaneous equations (the point gives you both an x and a y value)
What is the equation of a circle?
x^2 + y^2 = r^2
What is a tangent to a circle?
A line which just touches the circle once - it is always perpendicular to the radius of a circle
What is the angle between the tangent and the radius?
90 degrees
What does an inequality tell you?
When one value or expression is bigger or smaller than another value. You can represent inequalities on a number line
When drawing inequalities you mark a small circle at the end of your arrow mark - if the circle is open (empty) that means that…?
An open circle represents < or > and means that the number at the end of the arrow is NOT included
When drawing inequalities you mark a small circle at the end of your arrow mark - if the circle is closed (shaded in) that means that…?
A closed circle represents <= or >= and means that the number at the end of the arrow IS included
What is the rule for multiplying or dividing both sides of an inequality by a negative number?
If you multiply or divide both sides of an inequality by a negative number you have to reverse the inequality sign. EXAMPLE: -5x > 4 (/ -5)
x < - 4/5
What are integers?
Positive or negative whole numbers, including 0
What does the graph y = x^2 look like?
A downwards sloping curve
What is the difference between the trig graph of sin x and cos x?
They are the same shape, but y = sin x is translated 90 degrees to the right. So cos x is symmetrical about the y-axis (does not cross it) and sin x is symmetrical about the line x = 90 degrees (crosses the y-axis)
How often does the graph y = tan x repeat?
Every 180 degrees
Where are the asymptotes on the graph y = tan x?
There are asymptotes at -90 degrees, 90 degrees, 270 degrees, etc. The graph gets closer to these asymptotes but never reaches them
y = sin x is the same as…
y = cos (x - 90)
Explain the function of y = f(x) + a:
y = f(x) + a
Translation: ( O / a ) - WRITTEN AS A VECTOR
f(x) + a → move up a units
f(x) - a → move down a units
Explain the function of y = f(x + a):
y = f(x + a)
Translation: ( -a / O ) - WRITTEN AS A VECTOR
f(x + a) → move left a units
f(x - a) → move right a units
Explain the function of y = -f(x):
y = -f(x)
Reflection in the x-axis
Explain the function of y = f(-x)
y = f(-x)
Reflection in the y-axis
How do you find the turning point of a graph?
By writing the function in completed square form
What is the turning point of graph y = (x - a)^2 + b?
The graph of y = (x - a)^2 + b has a turning point at (a, b)
What are the roots of a function f(x)?
The roots of a function f(x) are the values of x for which f(x) = 0. This means that the roots of the function are the x-values at the points where y = f(x) crosses the x-axis
What should a sketch of a graph show?
All the major features, usually including turning points and places where the graph crosses the axis
When sketching cubic graphs, what are the 2 key things to remember?
- If one factor is x then the curve will pass through the origin
- If one factor is squared then the curve will just touch the x-axis at the corresponding point
What do we use iteration for?
Finding exact answers to more complicated questions, like those involving cubes or square roots. You can use iteration to find numerical answers to a given degree of accuracy
There is not only one iterative formula →
If you have to use an iteration formula to find the root or solve an equation, you will usually be given it in the exam. You will also usually be told what value of x↓O to use
What do we use an iteration formula to find?
The roots
What is the golden rule when simplifying algebraic fractions?
If the top or bottom of the fraction has more than one term, you will need to factorise before simplifying
Explain how to add or subtract algebraic fractions with different denominators:
- Find a common denominator
- Add or subtract the numerators
- Simplify if possible
Explain how to multiply algebraic fractions:
- Multiply the numerators AND multiply the denominators
- Simplify if possible
Explain how to divide algebraic fractions:
- Change the second fraction to its reciprocal
- Change / to X
- Multiply the fractions and simplify
How do you remove fractions from an equation?
Multiply everything by the LCM of the denominators
When expanding quadratics, what does FOIL stand for?
First Outer Inner Last
In f(x), what does f stand for?
Function
In f(x), what does x represent?
Input
How can you also write the composite function fg(x)?
f[g(x)]
What is a composite function?
A composite function is created if you apply 2 functions one after the other - it is a single function which has the same effect as the 2 combined functions
What is the inverse of a function?
For a function f, the inverse of f is the function that UNDOES f. Written as f^-1, if you apply f then f^-1 you will end up back where you started
How do you write the inverse of a function?
f^-1
How do you find the inverse of a function given in the form f(x)?
- Write the function in the form y = …
- Rearrange to make x the subject
- Swap any y’s for x’s and rewrite as f^-1(x) = …
What do you always have to use to prove something about numbers is true/false?
Algebra
Algebraic proof - how to represent an even number?
2n
Algebraic proof - how to represent an odd number?
2n + 1 OR 2n - 1
Algebraic proof - how to represent a multiple of 3?
3n
Algebraic proof - how to represent consecutive numbers?
n, n + 1, n + 2, n + 3…
Algebraic proof - how to represent consecutive even numbers?
2n, 2n + 2, 2n + 4, 2n + 6…
Algebraic proof - how to represent consecutive odd numbers?
2n + 1, 2n + 3, 2n + 5, 2n + 7…
Algebraic proof - how to represent consecutive square numbers?
n^2, (n + 1)^2, (n + 2)^2, (n + 3)^2…
What is an exponential function?
A function of the form f(x) = ka^x
What does the shape of an exponential graph depend on?
Whether x is positive or negative
What do exponential graphs generally represent in questions?
Growth or decay
How can you estimate the gradient of a curve?
You can estimate the gradient of a curve at a given point by drawing a tangent to the curve at that point. You can then draw a large triangle with that tangent line as the hypotenuse and calculate the gradient by dividing the height of the triangle by the base of the triangle
What is velocity?
Speed in a certain direction