-25n^2+90n=0

Solution for -25n^2+90n=0 equation:

-25n^2+90n=0

a = -25; b = 90; c = 0;
Δ = b2-4ac
Δ = 902-4·(-25)·0
Δ = 8100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{8100}=90$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(90)-90}{2*-25}=\frac{-180}{-50}
=3+3/5
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(90)+90}{2*-25}=\frac{0}{-50}
=0
$