Question

Without actually calculating the cubes find the value of -12X³ + 7³+5³

Answer 1

FORMULA USED

if a+b+c=0 then

$a {}^{} + b {}^{3} + c {}^{3} = 3abc \\ now \: here \\ ( - 12 + 7 + 5) = 0 \\ \\ so \\ ( - 12) {}^{3} + 7 {}^{} + 5 {}^{3} = 3 \times ( - 12) \times 7 \times 5 \\ = (- 36) \times 35 \\ = - 1260$