4x^2+80x-225=0

Solution for 4x^2+80x-225=0 equation:

4x^2+80x-225=0

a = 4; b = 80; c = -225;
Δ = b2-4ac
Δ = 802-4·4·(-225)
Δ = 10000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{10000}=100$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(80)-100}{2*4}=\frac{-180}{8}
=-22+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(80)+100}{2*4}=\frac{20}{8}
=2+1/2
$