(7x)2=441

Solution for (7x)2=441 equation:

(7x)2=441

We move all terms to the left:

(7x)2-(441)=0

We add all the numbers together, and all the variables

7x^2-441=0

a = 7; b = 0; c = -441;
Δ = b2-4ac
Δ = 02-4·7·(-441)
Δ = 12348
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:

$\sqrt{\Delta}=\sqrt{12348}=\sqrt{1764*7}=\sqrt{1764}*\sqrt{7}=42\sqrt{7}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-42\sqrt{7}}{2*7}=\frac{0-42\sqrt{7}}{14}
=-\frac{42\sqrt{7}}{14}
=-3\sqrt{7}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+42\sqrt{7}}{2*7}=\frac{0+42\sqrt{7}}{14}
=\frac{42\sqrt{7}}{14}
=3\sqrt{7}
$