$x=\frac{\sqrt{y\left(49y+4\right)}+y}{2y}$
$x=\frac{-\sqrt{y\left(49y+4\right)}+y}{2y}\text{, }y>0\text{ or }y\leq -\frac{4}{49}$

$y=\frac{1}{\left(x-4\right)\left(x+3\right)}$
$x\neq 4\text{ and }x\neq -3$