4(x^2+21-176)=0

Solution for 4(x^2+21-176)=0 equation:

4(x^2+21-176)=0

We multiply parentheses

4x^2+84-704=0

We add all the numbers together, and all the variables

4x^2-620=0

a = 4; b = 0; c = -620;
Δ = b2-4ac
Δ = 02-4·4·(-620)
Δ = 9920
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{9920}=\sqrt{64*155}=\sqrt{64}*\sqrt{155}=8\sqrt{155}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-8\sqrt{155}}{2*4}=\frac{0-8\sqrt{155}}{8}
=-\frac{8\sqrt{155}}{8}
=-\sqrt{155}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+8\sqrt{155}}{2*4}=\frac{0+8\sqrt{155}}{8}
=\frac{8\sqrt{155}}{8}
=\sqrt{155}
$