Question

Pls help i need step by step explanation

Answer 1

${31}^{3} - {30}^{3}$

$\implies {(3 0 + 1)}^{3} - {30}^{3}$

$\purple{ \sf{since : }}$

$\red{ \boxed{{(a + b)}^{3} = {a}^{3} + {b}^{3} + 3ab(a + b)}}$

$\implies \cancel{{30}^{3} } + {1}^{3} + 3(30)(1)(30 + 1) - \cancel{{30}^{3} }$

$\implies 1 + (90) ( 31 )$

$\implies 1 +27 90$

$\orange{\therefore 2791}$