If 2a + 3b = 8 and ab = 5. then find the value of $4a^2 + 9b^2$.

2 4  8 6

4

We know that, ( a + b )2 = a2 + b2 + 2ab If 2a + 3b = 8 ab = 5. then find the value of $4a^2 + 9b^2$ = ? ( 2a + 3b )2 = 4a2 + 9b2 + 2(6)(5) = 4a2 + 9b2 = 64 - 60 4a2 + 9b2 = 4