9 - binomial expansion

Question 1

to expand a term (a+b) ^n

Answer 1

(nC0) (a^n) (b^0)
+ (nC1) (a^n-1) (b^1)
+ (nC2) (a^n-2) (b^2) ….

Question 2

how to find the coefficient of a term eg x^2

Answer 2

use the chose function
or pascals triangle - which can be worked out using the chose function

Question 3

n!

Answer 3

n * (n-1) * (n-2) * … * 2 * 1

Question 4

nCr

Answer 4

n! / r!(n-r)!
these are known as binomial coefficients