Question

If x - 2y = 3 and .xy = 5, find the value of x^2-4y^2​

Answer 1

x - 2y = 3

x = 3 + 2y

xy = 5

(3 + 2y)y = 5

2y² + 3y - 5 = 0

2y² + 5y - 2y - 5 = 0

(2y + 5)(y - 1) = 0

y = 1 & x = 5

y = -5/2 & x = -2