x2+28x-198=0

Solution for x2+28x-198=0 equation:

x2+28x-198=0

We add all the numbers together, and all the variables

x^2+28x-198=0

a = 1; b = 28; c = -198;
Δ = b2-4ac
Δ = 282-4·1·(-198)
Δ = 1576
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:

$\sqrt{\Delta}=\sqrt{1576}=\sqrt{4*394}=\sqrt{4}*\sqrt{394}=2\sqrt{394}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-2\sqrt{394}}{2*1}=\frac{-28-2\sqrt{394}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+2\sqrt{394}}{2*1}=\frac{-28+2\sqrt{394}}{2}
$