Answer
$x=4$
Work Step by Step
$Given,$ $\sqrt x + 3=5$
$\sqrt x + 3-3=5-3$
$\sqrt x=2$
Squaring on both sides,
$x=4$
We need to check by putting the obtained value in the original equation:
$L.H.S=\sqrt 4+3=2+3=5=R.H.S$
Hence,$x=4$ is a valid solution