X^2+x^2+2x+7x-9=36

Solution for X^2+x^2+2x+7x-9=36 equation:

X^2+X^2+2X+7X-9=36

We move all terms to the left:

X^2+X^2+2X+7X-9-(36)=0

We add all the numbers together, and all the variables

2X^2+9X-45=0

a = 2; b = 9; c = -45;
Δ = b2-4ac
Δ = 92-4·2·(-45)
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-21}{2*2}=\frac{-30}{4}
=-7+1/2
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+21}{2*2}=\frac{12}{4}
=3
$