(65+x)(9+x)=0

Solution for (65+x)(9+x)=0 equation:

(65+x)(9+x)=0

We add all the numbers together, and all the variables

(x+65)(x+9)=0

We multiply parentheses ..

(+x^2+9x+65x+585)=0

We get rid of parentheses

x^2+9x+65x+585=0

We add all the numbers together, and all the variables

x^2+74x+585=0

a = 1; b = 74; c = +585;
Δ = b2-4ac
Δ = 742-4·1·585
Δ = 3136
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3136}=56$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(74)-56}{2*1}=\frac{-130}{2}
=-65
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(74)+56}{2*1}=\frac{-18}{2}
=-9
$