15x2=7.5

Solution for 15x2=7.5 equation:

15x^2=7.5

We move all terms to the left:

15x^2-(7.5)=0

We add all the numbers together, and all the variables

15x^2-7.5=0

a = 15; b = 0; c = -7.5;
Δ = b2-4ac
Δ = 02-4·15·(-7.5)
Δ = 450
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:

$\sqrt{\Delta}=\sqrt{450}=\sqrt{225*2}=\sqrt{225}*\sqrt{2}=15\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-15\sqrt{2}}{2*15}=\frac{0-15\sqrt{2}}{30}
=-\frac{15\sqrt{2}}{30}
=-\frac{\sqrt{2}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+15\sqrt{2}}{2*15}=\frac{0+15\sqrt{2}}{30}
=\frac{15\sqrt{2}}{30}
=\frac{\sqrt{2}}{2}
$