25y^2-400=0

Solution for 25y^2-400=0 equation:

25y^2-400=0

a = 25; b = 0; c = -400;
Δ = b2-4ac
Δ = 02-4·25·(-400)
Δ = 40000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{40000}=200$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-200}{2*25}=\frac{-200}{50}
=-4
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+200}{2*25}=\frac{200}{50}
=4
$