2v^2-81v-90=0

Solution for 2v^2-81v-90=0 equation:

2v^2-81v-90=0

a = 2; b = -81; c = -90;
Δ = b2-4ac
Δ = -812-4·2·(-90)
Δ = 7281
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{7281}=\sqrt{9*809}=\sqrt{9}*\sqrt{809}=3\sqrt{809}$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-81)-3\sqrt{809}}{2*2}=\frac{81-3\sqrt{809}}{4}
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-81)+3\sqrt{809}}{2*2}=\frac{81+3\sqrt{809}}{4}
$