Question

without actually calculating the cubes find 20^3+10^3-30^3

Answer 1

let 10 be x
$2 {x}^{3} + {x}^{3 } - 3 {x}^{3 } \\ {x}^{3} (2 + 1 - 3) \\ {x}^{3} (0) \\ 10 {}^{3} \times 0 \\ 0$

Answer 2

we know that if a+b+c = 0 then a^3 + b^3 + c^3 = 3abc
Now, 20+10+(-30)
30 - 30 = 0
Therefore 20^3 + 10^3 - 30^3 = 3(20)(10)(-30)
= -18000 is your answer