$x=-\sqrt{\frac{10-10y}{7}}$
$x=\sqrt{\frac{10-10y}{7}}$

$x=\frac{\sqrt{\frac{40-40y}{7}}}{2}$
$x=-\frac{\sqrt{\frac{40-40y}{7}}}{2}\text{, }y\leq 1$

$y=-\frac{7x^{2}}{10}+1$