Question 47724
{{{sqrt(2y + 7) + 4 = y }}}
First, hopefully, I understooed the question correctly.
Assuming you already know some algebraic manipulation, what you have to do here is to put the square root to one side. That is,
{{{sqrt(2y+7) = y - 4}}}
Then you can square both sides to get
{{{2y + 7 = y^2 - 8y +16 }}}
which simplifies to become
{{{y^2 - 10y + 9 = 0 }}}
which factorises to become
{{{ (y-9)(y-1) = 0 }}}
which means y = 1 or 9.