-2x^2+28x+26=0

Solution for -2x^2+28x+26=0 equation:

-2x^2+28x+26=0

a = -2; b = 28; c = +26;
Δ = b2-4ac
Δ = 282-4·(-2)·26
Δ = 992
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:

$\sqrt{\Delta}=\sqrt{992}=\sqrt{16*62}=\sqrt{16}*\sqrt{62}=4\sqrt{62}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-4\sqrt{62}}{2*-2}=\frac{-28-4\sqrt{62}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+4\sqrt{62}}{2*-2}=\frac{-28+4\sqrt{62}}{-4}
$