4(9+5x^2)=356

Solution for 4(9+5x^2)=356 equation:

4(9+5x^2)=356

We move all terms to the left:

4(9+5x^2)-(356)=0

We multiply parentheses

20x^2+36-356=0

We add all the numbers together, and all the variables

20x^2-320=0

a = 20; b = 0; c = -320;
Δ = b2-4ac
Δ = 02-4·20·(-320)
Δ = 25600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25600}=160$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-160}{2*20}=\frac{-160}{40}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+160}{2*20}=\frac{160}{40}
=4
$