Question

If a-b=8&a+b = -7 ,then 4ab What is your answer

Answer 1

Given,

a-b = 8   --------------- (1)

a+b = -7 --------------(2)

On squaring (1) we get:

(a-b)^2 = 64  ------------------------(3)

On squaring (2) we get:

(a+b)^2 =49 ------------------(4)

On subtracting (3) from (4) we get:

(a+b)^2 - (a-b)^2 = 49-64

or 4ab = -15

Answer 2

a-b=8,

a+b=-7

2a=1, a=½, b=a-8=-7-a=-7½.

4ab=4(½)(-7½)=(1)(-15)=-15.