Question

If x+y=7 and xy=11 find the value of x-y

Answer 1

Answer:

(a-b)^2 = a^2+b^2-2ab

(a+b)^2 = a^2+b^2+2ab

Subtract both the equation,

(a-b)^2 - (a+b)^2 = -4 ab

Replace a with x and b with y,

(x-y)^2 - ( x+y)^2 = -4xy

Given , x+y =7 and xy=11

(x-y)^2 - 49 = -44

= -44+49 = 5

(x-y) = root 5