4x^2+70x-400=0

Solution for 4x^2+70x-400=0 equation:

4x^2+70x-400=0

a = 4; b = 70; c = -400;
Δ = b2-4ac
Δ = 702-4·4·(-400)
Δ = 11300
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:

$\sqrt{\Delta}=\sqrt{11300}=\sqrt{100*113}=\sqrt{100}*\sqrt{113}=10\sqrt{113}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(70)-10\sqrt{113}}{2*4}=\frac{-70-10\sqrt{113}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(70)+10\sqrt{113}}{2*4}=\frac{-70+10\sqrt{113}}{8}
$