X^2+56x-784=0

Solution for X^2+56x-784=0 equation:

X^2+56X-784=0

a = 1; b = 56; c = -784;
Δ = b2-4ac
Δ = 562-4·1·(-784)
Δ = 6272
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:

$\sqrt{\Delta}=\sqrt{6272}=\sqrt{3136*2}=\sqrt{3136}*\sqrt{2}=56\sqrt{2}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(56)-56\sqrt{2}}{2*1}=\frac{-56-56\sqrt{2}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(56)+56\sqrt{2}}{2*1}=\frac{-56+56\sqrt{2}}{2}
$