3.5x^2=31.5

Solution for 3.5x^2=31.5 equation:

3.5x^2=31.5

We move all terms to the left:

3.5x^2-(31.5)=0

We add all the numbers together, and all the variables

3.5x^2-31.5=0

a = 3.5; b = 0; c = -31.5;
Δ = b2-4ac
Δ = 02-4·3.5·(-31.5)
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-21}{2*3.5}=\frac{-21}{7}
=-3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+21}{2*3.5}=\frac{21}{7}
=3
$