How do you use the binomial series to expand f(x)=1/(1+x)^3f(x)=1(1+x)3?

1 Answer
Nov 4, 2016

the answer is f(x)=1-3x+6x^2-10x^3+15x^4+.....

Explanation:

The binomial expansion is (a+b)^n
=a^n+na^(n-1)b+(n(n-1))/(1*2)a^(n-2)b^2+.......

Applying this here with a=1, b=x and n=-3
we get
f(x)=(1+x)^-3=1-3x+((-3)(-4))/(1*2)x^2+((-3)(-4)(-5))/(1*2*3)x^3+((-3)(-4)(-5)(-6))/(1*2*3*4)x^4+......
=1-3x+6x^2-10x^3+15x^4+.....