Write the term of the binomial series. Simplify.

Question

a. The term with b^5 in (a-b)^9
b. The seventh term of (x^1/2 + x^-1/2)^8

Answer 1

C(9,6)a^4(-b)^5 = -84a^4b^5

C(8,6)(x^1/2)^2*x^(-1/2)^6 = 28x^1*x^-3 = 28/x^2

Answer 2

C(9,5)a^4(-b)^5 = -126a^4b^5