(x+2)(9-7x)=0

Solution for (x+2)(9-7x)=0 equation:

(x+2)(9-7x)=0

We add all the numbers together, and all the variables

(x+2)(-7x+9)=0

We multiply parentheses ..

(-7x^2+9x-14x+18)=0

We get rid of parentheses

-7x^2+9x-14x+18=0

We add all the numbers together, and all the variables

-7x^2-5x+18=0

a = -7; b = -5; c = +18;
Δ = b2-4ac
Δ = -52-4·(-7)·18
Δ = 529
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{529}=23$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-23}{2*-7}=\frac{-18}{-14}
=1+2/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+23}{2*-7}=\frac{28}{-14}
=-2
$