Question

Solve: $5y^2-8y-128=0$

Answer 1

$5y^2-8y-128=0$

$a=5,b=-8$, $c=-128$

$y=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$

$y=\frac{8\pm \sqrt{64+2560}}{10}$

$y=\frac{8\pm \sqrt{26240}}{10}$

$y=\frac{8\pm 8\sqrt{41}}{10}$

$y=\frac{4\pm 4\sqrt{41}}{5}$

$\therefore y=\frac{4\pm 4\sqrt{41}}{5}$.