Question

without actually calculating the cubes find the value of each of the
$( { - 12})^{3 } + ( {7)}^{3} + ( {5)}^{3}$
​

Answer 1

We know by formula that

(a)^3 +(b)^3 +(c)^3= 3×a×b×c

ONLY IF a+b+c=0

Now here,

a= -12

b=7

c=5

a+b+c= -12 +7 +5 = -12+12=0

since their sum is zero

-12^3 +7^3 +5^3= 3× (-12) ×7 ×5

= -36×35

=-1260