-17x(x+9)=28

Solution for -17x(x+9)=28 equation:

-17x(x+9)=28

We move all terms to the left:

-17x(x+9)-(28)=0

We multiply parentheses

-17x^2-153x-28=0

a = -17; b = -153; c = -28;
Δ = b2-4ac
Δ = -1532-4·(-17)·(-28)
Δ = 21505
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{-(-153)-\sqrt{21505}}{2*-17}=\frac{153-\sqrt{21505}}{-34}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-153)+\sqrt{21505}}{2*-17}=\frac{153+\sqrt{21505}}{-34}
$