5x^2+70x-800=0

Solution for 5x^2+70x-800=0 equation:

5x^2+70x-800=0

a = 5; b = 70; c = -800;
Δ = b2-4ac
Δ = 702-4·5·(-800)
Δ = 20900
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:

$\sqrt{\Delta}=\sqrt{20900}=\sqrt{100*209}=\sqrt{100}*\sqrt{209}=10\sqrt{209}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(70)-10\sqrt{209}}{2*5}=\frac{-70-10\sqrt{209}}{10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(70)+10\sqrt{209}}{2*5}=\frac{-70+10\sqrt{209}}{10}
$