7x^2-644=0

Solution for 7x^2-644=0 equation:

7x^2-644=0

a = 7; b = 0; c = -644;
Δ = b2-4ac
Δ = 02-4·7·(-644)
Δ = 18032
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:

$\sqrt{\Delta}=\sqrt{18032}=\sqrt{784*23}=\sqrt{784}*\sqrt{23}=28\sqrt{23}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-28\sqrt{23}}{2*7}=\frac{0-28\sqrt{23}}{14}
=-\frac{28\sqrt{23}}{14}
=-2\sqrt{23}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+28\sqrt{23}}{2*7}=\frac{0+28\sqrt{23}}{14}
=\frac{28\sqrt{23}}{14}
=2\sqrt{23}
$