7x^2+35x-35=0

Solution for 7x^2+35x-35=0 equation:

7x^2+35x-35=0

a = 7; b = 35; c = -35;
Δ = b2-4ac
Δ = 352-4·7·(-35)
Δ = 2205
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:

$\sqrt{\Delta}=\sqrt{2205}=\sqrt{441*5}=\sqrt{441}*\sqrt{5}=21\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(35)-21\sqrt{5}}{2*7}=\frac{-35-21\sqrt{5}}{14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(35)+21\sqrt{5}}{2*7}=\frac{-35+21\sqrt{5}}{14}
$