Question 245464
Factor:
{{{125r^3+1}}} As you have pointed out, this is the sum of two cubes:
{{{(5r)^3+(1)^3}}}
The sum of two cubes is factored thus:
{{{A^3+B^3 = (A+B)(A^2-AB+B^2)}}} and here, {{{A = 5r}}}, {{{B = 1}}}, so...
{{{125r^3+1 = (5r+1)(25r^2-5r+1)}}}