Question

Using suitable identity, evaluate $(-13{)}^3+(5{)}^3+(8{)}^3$

Answer 1

Using identity

$a^3+b^3+c^3=3abc$ if $a+b+c=$

Here $a=-13,b=5$ and $c=8$

$\Rightarrow a+b+c=-13+5+8=0$

$\therefore (-13{)}^3+(5{)}^3+(8{)}^3=3[(-13)\left(5\right)\left(8\right)]$

$=3\left[\right(520]$

$=-1560$