Question 842683
Treat y as a constant.  You can then either complete the square to find formulas for x, or you can directly use the general solution to a quadratic equation.


Again, if y is a constant, then {{{x^2+4x-6-y=0}}}
{{{x^2+4x-(y+6)=0}}}.
Use Completion of Square if you want, but if you know the general solution process using it, then you know how to use the result for x.


{{{highlight(x=(-4+- sqrt(16+4(y+6)))/2)}}}   ----- I condensed a couple of steps there.
{{{x=-2+- sqrt(4+y+6)}}}
{{{highlight(highlight(x=-2+- sqrt(y+10)))}}} ---- most simplified