(3x+5)(3x+5)=36

Solution for (3x+5)(3x+5)=36 equation:

(3x+5)(3x+5)=36

We move all terms to the left:

(3x+5)(3x+5)-(36)=0

We multiply parentheses ..

(+9x^2+15x+15x+25)-36=0

We get rid of parentheses

9x^2+15x+15x+25-36=0

We add all the numbers together, and all the variables

9x^2+30x-11=0

a = 9; b = 30; c = -11;
Δ = b2-4ac
Δ = 302-4·9·(-11)
Δ = 1296
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1296}=36$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(30)-36}{2*9}=\frac{-66}{18}
=-3+2/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(30)+36}{2*9}=\frac{6}{18}
=1/3
$