330=x(x+7)

Solution for 330=x(x+7) equation:

330=x(x+7)

We move all terms to the left:

330-(x(x+7))=0


We calculate terms in parentheses: -(x(x+7)), so:

x(x+7)

We multiply parentheses

x^2+7x

Back to the equation:

-(x^2+7x)


We get rid of parentheses

-x^2-7x+330=0

We add all the numbers together, and all the variables

-1x^2-7x+330=0

a = -1; b = -7; c = +330;
Δ = b2-4ac
Δ = -72-4·(-1)·330
Δ = 1369
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1369}=37$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-37}{2*-1}=\frac{-30}{-2}
=+15
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+37}{2*-1}=\frac{44}{-2}
=-22
$