25n^2-10=90

Solution for 25n^2-10=90 equation:

25n^2-10=90

We move all terms to the left:

25n^2-10-(90)=0

We add all the numbers together, and all the variables

25n^2-100=0

a = 25; b = 0; c = -100;
Δ = b2-4ac
Δ = 02-4·25·(-100)
Δ = 10000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{10000}=100$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-100}{2*25}=\frac{-100}{50}
=-2
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+100}{2*25}=\frac{100}{50}
=2
$