Question

If a2+b2-4(a+b)= -8,then the value of (a-b) is: A. 4 B. 0 C. 2 D. 8

Answer 1

a²+b²-4(a+b)= -8

a² - 4a - 4b + b² = -8.

a(a - 4) - b(4 - b) = -8.

By hit and trial method we get the values of a and b.

Let us assume that a = b = 2.

2(2 - 4) - 2(4 - 2)

or, 2 * (-2) - 2 * (2)

or, - 4 - 4 = -8 = RHS.

Therefore,

(a-b) = 2 - 2 = 0. i.e. option no B.