(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)+45*5=0

We add all the numbers together, and all the variables

-((x+7)*x)+225=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+225=0

We add all the numbers together, and all the variables

-1x^2-7x+225=0

a = -1; b = -7; c = +225;
Δ = b2-4ac
Δ = -72-4·(-1)·225
Δ = 949
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{949}}{2*-1}=\frac{7-\sqrt{949}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+\sqrt{949}}{2*-1}=\frac{7+\sqrt{949}}{-2}
$