4x2+90x-644=0

Solution for 4x2+90x-644=0 equation:

4x^2+90x-644=0

a = 4; b = 90; c = -644;
Δ = b2-4ac
Δ = 902-4·4·(-644)
Δ = 18404
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{18404}=\sqrt{4*4601}=\sqrt{4}*\sqrt{4601}=2\sqrt{4601}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(90)-2\sqrt{4601}}{2*4}=\frac{-90-2\sqrt{4601}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(90)+2\sqrt{4601}}{2*4}=\frac{-90+2\sqrt{4601}}{8}
$