-2x(-14-3x)=9

Solution for -2x(-14-3x)=9 equation:

-2x(-14-3x)=9

We move all terms to the left:

-2x(-14-3x)-(9)=0

We add all the numbers together, and all the variables

-2x(-3x-14)-9=0

We multiply parentheses

6x^2+28x-9=0

a = 6; b = 28; c = -9;
Δ = b2-4ac
Δ = 282-4·6·(-9)
Δ = 1000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1000}=\sqrt{100*10}=\sqrt{100}*\sqrt{10}=10\sqrt{10}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-10\sqrt{10}}{2*6}=\frac{-28-10\sqrt{10}}{12}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+10\sqrt{10}}{2*6}=\frac{-28+10\sqrt{10}}{12}
$