x(2x+9)=980

Solution for x(2x+9)=980 equation:

x(2x+9)=980

We move all terms to the left:

x(2x+9)-(980)=0

We multiply parentheses

2x^2+9x-980=0

a = 2; b = 9; c = -980;
Δ = b2-4ac
Δ = 92-4·2·(-980)
Δ = 7921
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{7921}=89$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-89}{2*2}=\frac{-98}{4}
=-24+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+89}{2*2}=\frac{80}{4}
=20
$