Question

3a +7b =20 and Ab=4 find value of 9a square +49b square ..please send fast... ​

Answer 1

a²+b² = (a+b)² - 2ab

a = 3a

b = 7b

So

9a²+49b² = ( 3a+7b)² - 2ab

Substituting the values we get

9a²+49b² = 400-8

= 392