7=4x^2

Solution for 7=4x^2 equation:

7=4x^2

We move all terms to the left:

7-(4x^2)=0

a = -4; b = 0; c = +7;
Δ = b2-4ac
Δ = 02-4·(-4)·7
Δ = 112
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:

$\sqrt{\Delta}=\sqrt{112}=\sqrt{16*7}=\sqrt{16}*\sqrt{7}=4\sqrt{7}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-4\sqrt{7}}{2*-4}=\frac{0-4\sqrt{7}}{-8}
=-\frac{4\sqrt{7}}{-8}
=-\frac{\sqrt{7}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+4\sqrt{7}}{2*-4}=\frac{0+4\sqrt{7}}{-8}
=\frac{4\sqrt{7}}{-8}
=\frac{\sqrt{7}}{-2}
$