10(3x^2-8)=40

Solution for 10(3x^2-8)=40 equation:

10(3x^2-8)=40

We move all terms to the left:

10(3x^2-8)-(40)=0

We multiply parentheses

30x^2-80-40=0

We add all the numbers together, and all the variables

30x^2-120=0

a = 30; b = 0; c = -120;
Δ = b2-4ac
Δ = 02-4·30·(-120)
Δ = 14400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{14400}=120$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-120}{2*30}=\frac{-120}{60}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+120}{2*30}=\frac{120}{60}
=2
$