x^2+66x-65,4375=0

Solution for x^2+66x-65,4375=0 equation:

x^2+66x-65.4375=0

a = 1; b = 66; c = -65.4375;
Δ = b2-4ac
Δ = 662-4·1·(-65.4375)
Δ = 4617.75
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(66)-\sqrt{4617.75}}{2*1}=\frac{-66-\sqrt{4617.75}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(66)+\sqrt{4617.75}}{2*1}=\frac{-66+\sqrt{4617.75}}{2}
$