Find the first three terms in the expansion of (4-x)^(-1/2) in ascending powers of x.

(4-x)^-1/2 = (4 (1 - x/4))^-1/2 = 1/2 (1 - x/4)^-1/2 = 1/2 ( 1 + x/8 + 3x²/128 + ...) = 1/2 + x/16 + 3x²/256 + ...Therefore the first three terms are 1/2 + x/16 + 3x²/256