Expand the binomials on the left-hand side of the equation and simplify:
\((a-1)^3=a^3-3a^2+3a-1\\ (a-1)^2=a^2-2a+1\) | Let's put this together into one cohesive expression. |
\(a^3-3a^2+3a-1+a^2-2a+1\) | Combine like terms. |
\(a^3-2a^2+a\) | Factor out an a . |
\(a(a^2-2a+1)\) | The trinomial is indeed factorable and happens to factor into a perfect square. |
\(a(a-1)(a-1)\) | |
\(a(a-1)^2\) | |