10=2.5x^2

Solution for 10=2.5x^2 equation:

10=2.5x^2

We move all terms to the left:

10-(2.5x^2)=0

We get rid of parentheses

-2.5x^2+10=0

a = -2.5; b = 0; c = +10;
Δ = b2-4ac
Δ = 02-4·(-2.5)·10
Δ = 100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{100}=10$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-10}{2*-2.5}=\frac{-10}{-5}
=+2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+10}{2*-2.5}=\frac{10}{-5}
=-2
$