1.25x^2=20

Solution for 1.25x^2=20 equation:

1.25x^2=20

We move all terms to the left:

1.25x^2-(20)=0

a = 1.25; b = 0; c = -20;
Δ = b2-4ac
Δ = 02-4·1.25·(-20)
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*1.25}=\frac{-10}{2.5}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+10}{2*1.25}=\frac{10}{2.5}
=4
$