4(7+5x^2)=748

Solution for 4(7+5x^2)=748 equation:

4(7+5x^2)=748

We move all terms to the left:

4(7+5x^2)-(748)=0

We multiply parentheses

20x^2+28-748=0

We add all the numbers together, and all the variables

20x^2-720=0

a = 20; b = 0; c = -720;
Δ = b2-4ac
Δ = 02-4·20·(-720)
Δ = 57600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{57600}=240$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-240}{2*20}=\frac{-240}{40}
=-6
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+240}{2*20}=\frac{240}{40}
=6
$