X^2+4x-85=0

Solution for X^2+4x-85=0 equation:

X^2+4X-85=0

a = 1; b = 4; c = -85;
Δ = b2-4ac
Δ = 42-4·1·(-85)
Δ = 356
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:

$\sqrt{\Delta}=\sqrt{356}=\sqrt{4*89}=\sqrt{4}*\sqrt{89}=2\sqrt{89}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-2\sqrt{89}}{2*1}=\frac{-4-2\sqrt{89}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+2\sqrt{89}}{2*1}=\frac{-4+2\sqrt{89}}{2}
$