25=3*x^2

Solution for 25=3*x^2 equation:

25=3x^2

We move all terms to the left:

25-(3x^2)=0

a = -3; b = 0; c = +25;
Δ = b2-4ac
Δ = 02-4·(-3)·25
Δ = 300
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:

$\sqrt{\Delta}=\sqrt{300}=\sqrt{100*3}=\sqrt{100}*\sqrt{3}=10\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-10\sqrt{3}}{2*-3}=\frac{0-10\sqrt{3}}{-6}
=-\frac{10\sqrt{3}}{-6}
=-\frac{5\sqrt{3}}{-3}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+10\sqrt{3}}{2*-3}=\frac{0+10\sqrt{3}}{-6}
=\frac{10\sqrt{3}}{-6}
=\frac{5\sqrt{3}}{-3}
$