Question

if (3ab - 2b) = 9, ab =7 then find (9a square + 2b square)

Answer 1

(3a - 2b)^2 = (3a)^2 + (2b)^2 - 2×3a×2b
(9)^2) = 9a^2 + 4b^2 -12×7
9a^2 + 4b^2 =81 + 84
= 165

Answer 2

Something is written wrong in your question, kindly check it.

Solution is :-

(3a-2b) =9

Square on both sides,

(3a-2b)²=9²

9a²+4b²-2(6ab) =81

Put the given values,

9a²+2b²-(12*7)=81

9a²+2b²=81+84

9a²+2b²=165