2x+(x-4)(x+1)=9

Solution for 2x+(x-4)(x+1)=9 equation:

2x+(x-4)(x+1)=9

We move all terms to the left:

2x+(x-4)(x+1)-(9)=0

We multiply parentheses ..

(+x^2+x-4x-4)+2x-9=0

We get rid of parentheses

x^2+x-4x+2x-4-9=0

We add all the numbers together, and all the variables

x^2-1x-13=0

a = 1; b = -1; c = -13;
Δ = b2-4ac
Δ = -12-4·1·(-13)
Δ = 53
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{-(-1)-\sqrt{53}}{2*1}=\frac{1-\sqrt{53}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+\sqrt{53}}{2*1}=\frac{1+\sqrt{53}}{2}
$