(square root of a + 3 square root of b /a - b) - (2/square root of a + square root of b).

Answer 1

(√a + 3√b)/(a-b) - 2/(√a+√b)

Note that (√a-√b)(√a+√b) = a-b, so

(√a + 3√b)/(a-b) - 2/(√a+√b) * (√a-√b)/(√a-√b)

(√a+3√b)/(a-b) - 2(√a-√b)/(a-b)

(√a+3√b-2√a+2√b)/(a-b)

(-√a+5√b)/(a-b)