Year 1 Pure Facts/Rules Flashcards
What is the quadratic formula?
x=(-b±√(b^2-4ac))/2a
What is the discriminant?
b^2-4ac
How do you determine if a quadratic equation has no real roots?
The discriminant is negative
ie b^2-4ac<0
or b^2<4ac
How do you determine if a quadratic equation has equal (repeated) real roots?
The discriminant equals zero
ie b^2-4ac=0
or b^2=4ac
How do you determine if a quadratic equation has two real roots?
The discriminant is positive
ie b^2-4ac>0
or b^2>4ac
If you are sketching a cubic graph that has a positive x3 term, where does your sketch start - bottom left or top left?
Bottom left
How do we find the points at which a quadratic function crosses the x-axis?
Put y = 0 and solve the quadratic equation by factorising, completing the square or using the formula. The x-axis crossing points are the solutions (the ‘roots’) of the equation.
If we have completed the square to get
〖y= (x+3)〗^2+19
what are the coordinates of the minimum point of this quadratic function?
(-3,19)
Factorise x^2-y^2
(x-y)(x+y)
Complete the square: x^2-8x
(x-4)^2-16
What is the value of 〖64〗^(1/3)?
4
What is the value of 〖11〗^(-2)?
1/121
Simplify √50
5√2
How would you rationalise the denominator of 1/(a+√b)?
Multiply by (a-√b)/(a-√b)
How do you find the gradient of the straight line joining two points?
m= rise/run=(change in y)/(change in x)= (y_2-y_1)/(x_2-x_1 )
What method should you use to solve simultaneous equations where one is linear and one is quadratic?
Substitution
When solving an inequality, what must you do if you multiply or divide both sides by a negative number?
Turn the inequality sign around
What must you do when solving a quadratic inequality?
Draw a sketch
If the straight line L has gradient m, what is the gradient of the straight line perpendicular to L?
-1/m (ie the negative reciprocal)
If a tangent to a curve at the point P has gradient-2/3, what is the gradient of the normal to the curve at the point P?
3/2
The point A(3,5) lies on the curve y = f(x).
What are the new coordinates of the point A under the transformation y = f(-x)?
( -3 , 5 )