x2-80x-225=0

Solution for x2-80x-225=0 equation:

x2-80x-225=0

We add all the numbers together, and all the variables

x^2-80x-225=0

a = 1; b = -80; c = -225;
Δ = b2-4ac
Δ = -802-4·1·(-225)
Δ = 7300
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:

$\sqrt{\Delta}=\sqrt{7300}=\sqrt{100*73}=\sqrt{100}*\sqrt{73}=10\sqrt{73}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-80)-10\sqrt{73}}{2*1}=\frac{80-10\sqrt{73}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-80)+10\sqrt{73}}{2*1}=\frac{80+10\sqrt{73}}{2}
$