Question

So, I need someone to help show me the steps for solving the equation after equal sign. It is supposed to = 729, and I am pretty sure it does and it's true, but everytime I try to prove it I must be doing something wrong because I get insane answers instead.. Can someone help me and show the steps to getting 729 for this polynomial? Thanks!
(4+5)(4+5)(4+5) = 4^3+3(4)^2(5)+3(4)(5)^2+(5)^3

Answer 1

4^3+3(4)^2(5)+3(4)(5)^2+(5)^3
64 + 3*16*5 + 12*25 + 125
64 + 240 + 300 + 125
729