(5-x)(5-x)2=7

Solution for (5-x)(5-x)2=7 equation:

(5-x)(5-x)2=7

We move all terms to the left:

(5-x)(5-x)2-(7)=0

We add all the numbers together, and all the variables

(-1x+5)(-1x+5)2-7=0

We multiply parentheses ..

(+x^2-5x-5x+25)2-7=0

We multiply parentheses

2x^2-10x-10x+50-7=0

We add all the numbers together, and all the variables

2x^2-20x+43=0

a = 2; b = -20; c = +43;
Δ = b2-4ac
Δ = -202-4·2·43
Δ = 56
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:

$\sqrt{\Delta}=\sqrt{56}=\sqrt{4*14}=\sqrt{4}*\sqrt{14}=2\sqrt{14}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-2\sqrt{14}}{2*2}=\frac{20-2\sqrt{14}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+2\sqrt{14}}{2*2}=\frac{20+2\sqrt{14}}{4}
$