(9+5)5=(7+x)x

Solution for (9+5)5=(7+x)x equation:

(9+5)5=(7+x)x

We move all terms to the left:

(9+5)5-((7+x)x)=0

We add all the numbers together, and all the variables

-((x+7)x)+145=0


We calculate terms in parentheses: -((x+7)x), so:

(x+7)x

We multiply parentheses

x^2+7x

Back to the equation:

-(x^2+7x)


We get rid of parentheses

-x^2-7x+145=0

We add all the numbers together, and all the variables

-1x^2-7x+145=0

a = -1; b = -7; c = +145;
Δ = b2-4ac
Δ = -72-4·(-1)·145
Δ = 629
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-\sqrt{629}}{2*-1}=\frac{7-\sqrt{629}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+\sqrt{629}}{2*-1}=\frac{7+\sqrt{629}}{-2}
$