Question 171490
First fraction:
{{{(x^3+125)/(x^3-125)}}}
simplify using formula  a^3+b^3=(a+b)(a^2-ab+b^2) and a^3-b^3=(a-b)(a^2+ab+b^2)
x^3+125=x^3+5^3= (x+5)(x^2-5x+25)
similary do with (x^3-125)
then:
{{{((x+5)(x^2-5x+25))/((x-5)(x^2+5x+25))}}}
Now first fraction multiply by inverse of second and simplify
{{{((x+5)(x^2-5x+25))/((x-5)(x^2+5x+25))}}}* {{{(x-5)/(x^2-5x+25)}}}={{{(x+5)/(x^2+5x+25)}}}
*** you can not simplify x^2-5x+25 because it doesnt have roots b^2-4ac<0