Question 175717
{{{1^3-5b^3}}}
:
difference of cubes formula
:
{{{a^3-b^3=(a-b)(a^2+ab+b^2)}}} 
:
so set a=1 and b=5b and plug it into that formula
:
{{{(1-5b)(1+5b+(5b)^2)}}}
:
{{{highlight((1-5b)(1+5b+25b^2))}}}