User:ROsattin/sandbox


 * $$\begin{align}

\sqrt(x-7) &= x-7 \\ x-7 &= (x-7)^2 \\ x-7 &= x^2-14x+49 \\ -7 &= x^2-15x+49 \\ 0 &= x^2-15x+54 \\ 0 &= (x-7)(x-8) \\ x&=7 \\ x&=8

\end{align}$$