-4t^2+225=0

Solution for -4t^2+225=0 equation:

-4t^2+225=0

a = -4; b = 0; c = +225;
Δ = b2-4ac
Δ = 02-4·(-4)·225
Δ = 3600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3600}=60$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-60}{2*-4}=\frac{-60}{-8}
=7+1/2
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+60}{2*-4}=\frac{60}{-8}
=-7+1/2
$