320=(2x+9)(x)

Solution for 320=(2x+9)(x) equation:

320=(2x+9)(x)

We move all terms to the left:

320-((2x+9)(x))=0


We calculate terms in parentheses: -((2x+9)x), so:

(2x+9)x

We multiply parentheses

2x^2+9x

Back to the equation:

-(2x^2+9x)


We get rid of parentheses

-2x^2-9x+320=0

a = -2; b = -9; c = +320;
Δ = b2-4ac
Δ = -92-4·(-2)·320
Δ = 2641
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{-(-9)-\sqrt{2641}}{2*-2}=\frac{9-\sqrt{2641}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+\sqrt{2641}}{2*-2}=\frac{9+\sqrt{2641}}{-4}
$