Question 557686
"difference of cubes":
a^3 – b^3 = (a – b)(a^2 + ab + b^2)
.
since you have:
4a^2(a^3-125)
we can rewrite as:
4a^2(a^3-5^3)
so, now we have:
4a^2(a-5)(a^2-5a+5^2)
4a^2(a-5)(a^2-5a+25)