Question

if a²+b²=9 and ab=4 find the value of 3(a+b)²-2(a-b)²

Answer 1

(a+b)²=a²+b²+2ab
=9+2(4)
=17
(a-b)²=a²+b²-2ab
=9-2(4)
=1
3(a+b)²-2(a-b)²=3(17)-2(1)
=61-2
=59

Answer 2

a²+b²=9
ab=4

3(a+b)²-2(a-b)²
3(a²+b²+2.a.b)-2(a²+b²-2.a.b)
3(9+2×4)-2(9-2×4)
3(9+8)-2(9-8)
3(17)-2(1)
51-2
49:ans