If a + b = 24 and 8ab = 256, then what is the value of 3a^2 + 3b^2 ?

If a + b = 24

8ab = 256,

then what is the value of $ 3a^2 + 3b^2 $

If 8ab = 256, 

then, ab = 32

$ 3(a^2 + b^2) $= 3 ×( 24² - 2 × 32)

$ 3(a^2 + b^2) $ = 3 ×( 576 - 64)

$ 3(a^2 + b^2) $ =3 × 512 = 1536