90=(x^2)+(8x+25)

Solution for 90=(x^2)+(8x+25) equation:

90=(x^2)+(8x+25)

We move all terms to the left:

90-((x^2)+(8x+25))=0


We calculate terms in parentheses: -(x^2+(8x+25)), so:

x^2+(8x+25)

We get rid of parentheses

x^2+8x+25

Back to the equation:

-(x^2+8x+25)


We get rid of parentheses

-x^2-8x-25+90=0

We add all the numbers together, and all the variables

-1x^2-8x+65=0

a = -1; b = -8; c = +65;
Δ = b2-4ac
Δ = -82-4·(-1)·65
Δ = 324
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{324}=18$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-18}{2*-1}=\frac{-10}{-2}
=+5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+18}{2*-1}=\frac{26}{-2}
=-13
$