Question

if a-b=15 and ab =100, then find a2+b2

Answer 1

Ans.

(a-b)^2 = a^2 + b^2 - 2ab
or, (15)^2 = a^2 + b^2 - (2×100)
or, 225 = a^2 + b^2 - 200
or, a^2 + b^2 = 425.

I HOPE THAT THIS HELPS YOU.

Answer 2

So,
a = 15 + b
Then,
ab = 100
(15+b) b = 100
b² +15b - 100 = 0
b² + 20b -5b -100 = 0
b(b+20) -5(b+ 20) = 0
(b+20)(b-5) = 0
b = -20 or 5
a = -5 or 20
So from this,
2(a+b) = 2(-5-20) or 2(5+20)
= -50 or 50 (Answer)....