1.25x^2-90x+72=0

Solution for 1.25x^2-90x+72=0 equation:

1.25x^2-90x+72=0

a = 1.25; b = -90; c = +72;
Δ = b2-4ac
Δ = -902-4·1.25·72
Δ = 7740
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:

$\sqrt{\Delta}=\sqrt{7740}=\sqrt{36*215}=\sqrt{36}*\sqrt{215}=6\sqrt{215}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-90)-6\sqrt{215}}{2*1.25}=\frac{90-6\sqrt{215}}{2.5}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-90)+6\sqrt{215}}{2*1.25}=\frac{90+6\sqrt{215}}{2.5}
$