If a - b = 8 and 4ab = 84, then what is the value of $3a^2 - 3b^2$ ?

1016 2032 1018 3048

3048

We know = a³ - b³ = (a - b)(a² + ab + b²) a - b = 8 4ab = 84 ab = 21 = 3a³ - 3b³ = 3(a³ - b³) = 3(a - b)(a² + ab + b²) = (a - b)2 = a2 + b2 - 2ab = 82 = a2 + b2  - 2 × 21 = 64 = a2 + b2  - 42 = a2 + b2  = 106 Put the all values  in3(a - b)(a² + ab + b²) = 3 × 8 × (106 + 21) = 3048