(x)(x+3)=66

Solution for (x)(x+3)=66 equation:

(x)(x+3)=66

We move all terms to the left:

(x)(x+3)-(66)=0

We multiply parentheses

x^2+3x-66=0

a = 1; b = 3; c = -66;
Δ = b2-4ac
Δ = 32-4·1·(-66)
Δ = 273
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{-(3)-\sqrt{273}}{2*1}=\frac{-3-\sqrt{273}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+\sqrt{273}}{2*1}=\frac{-3+\sqrt{273}}{2}
$