5x^2+720x-280=0

Solution for 5x^2+720x-280=0 equation:

5x^2+720x-280=0

a = 5; b = 720; c = -280;
Δ = b2-4ac
Δ = 7202-4·5·(-280)
Δ = 524000
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:

$\sqrt{\Delta}=\sqrt{524000}=\sqrt{400*1310}=\sqrt{400}*\sqrt{1310}=20\sqrt{1310}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(720)-20\sqrt{1310}}{2*5}=\frac{-720-20\sqrt{1310}}{10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(720)+20\sqrt{1310}}{2*5}=\frac{-720+20\sqrt{1310}}{10}
$