Let <em>y</em> = √(<em>x</em> - 10), so that <em>y</em>² = <em>x</em> - 10.
Then <em>x</em> = <em>y</em>² + 10 so that √<em>x</em> = ±√(<em>y</em>² + 10).
So we've rewritten the equation as
<em>y</em> = ±√(<em>y</em>² + 10)
In either case, squaring both sides gives
<em>y</em>² = <em>y</em>² + 10
and eliminating <em>y</em>² gives us the false result
0 = 10
so there is no solution.