sequences Flashcards
Nth term of a quadratic sequence?
N[squared]
Nth term of a triangular sequence and how to spot?
[half]n(n+1)
Can spot by finding the difference and if it goes up by one each time
How work out a geometric sequence/powers of 2 etc
Find what it is multiplied by each time and then it will be that number to the power of n e.g. 2[power of n]
What is the first 5 numbers in the n[squared sequence] and how do you find the nth term?
1,4,9,16,25
If the difference is going up in odd numbers the it is n[squared] and then find the difference between the quadratic sequence and you sequence. If it starts a place ahead of the usual sequence the you just add 1 to n so it would be (n+1)[all squared]
How do you work out the gradient of a straight line?
1) draw a triangle from the line connecting 2 points
2) divide the difference in y by the difference in x
what does m and c stand for in the equation y = mx + c?
m = gradient c = y intercept
How do you work out the equation of a line where you have only been given one of the points?
1) substitute the gradient for m in y = mx + c
2) substitute in the x and y values
3) solve to find c
4) re arrange into the equation y = mx + c
How do you identify a Fibonacci sequence?
If the 2 previous numbers add up to make the next number
How do you find the missing terms in a Fibonacci sequence?
replace the numbers with algebra so that the first number is a and the second is b so: a, b, a+b, a+2b….
then use that to find the missing numbers
How do you recognise a cubic sequence and what is the nth term?
1) if the 3rd difference is 6
2) n[3] + the difference between your sequence and a cubic sequence (1,8,27,65)
How do you spot a geometric sequence?
if the numbers get multiplied by the same number to get the next number in the sequence
