Question

The value of (-3)${}^3$ + (7)${}^3$ + (-4)${}^3$ is :

• A. 252
• B. 264
• C. 121
• D. 343

Answer 1

The correct option is A 252

In the identity ,($a+b+c$)($a^2+b^2+c^2-ab-bc-ca$) = $a^3+b^3+c^3-3abc$ , if ($a+b+c$) = 0 , then $a^3+b^3+c^3=3abc$.
Since, (-3)+(-4)+(7) = 0.
Hence, (-3)${}^3$ + (7)${}^3$ + (-4)${}^3$ = 3(-3)(-4)(7) = 252.