[tex]\bf 5-\sqrt{x+10}=\sqrt{7-x}\impliedby \textit{squaring both sides}
\\\\\\
(5-\sqrt{x+10})^2=(\sqrt{7-x})^2
\\\\\\
(5^2)-10\sqrt{x+10}+(x+10)=7-x
\\\\\\
35-10\sqrt{x+10}+x=7-x\implies 28-10\sqrt{x+10}+2x=0
\\\\\\
2x+28=10\sqrt{x+10}\implies x+14=5\sqrt{x+10}\impliedby
\begin{array}{llll}
squaring\ both\\
sides\ again
\end{array}
\\\\\\
[/tex]
[tex]\bf (x^2)+28x+(14^2)=5^2(x+10)\implies x^2+28x+196=25x+250
\\\\\\
\begin{array}{lcclll}
x^2&+3x&-54&=0\\
&\uparrow &\uparrow \\
&-6+9&-6\cdot 9
\end{array} \implies (x+9)(x-6)=0\implies
\begin{cases}
x+9=0\\
\boxed{x=-9}\\
-----\\
x-6=0\\
\boxed{x=6}
\end{cases}[/tex]
