Question

Without actually calculating the cubes, find the values of the following:
${\left(28\right)}^3+{(-15)}^3+{(-13)}^3$

Answer 1

$(28{)}^3+(-15{)}^3+(-13{)}^3=0$

because

$28+(-15)+(-13)=0$

this is because $a^3+b^3+c^3=(a+b+c)(a^2+b^2+c^2-ab-bc-ac)$