x^2+4x=870

Solution for x^2+4x=870 equation:

x^2+4x=870

We move all terms to the left:

x^2+4x-(870)=0

a = 1; b = 4; c = -870;
Δ = b2-4ac
Δ = 42-4·1·(-870)
Δ = 3496
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:

$\sqrt{\Delta}=\sqrt{3496}=\sqrt{4*874}=\sqrt{4}*\sqrt{874}=2\sqrt{874}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-2\sqrt{874}}{2*1}=\frac{-4-2\sqrt{874}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+2\sqrt{874}}{2*1}=\frac{-4+2\sqrt{874}}{2}
$