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

Solution for (4x-2)(x+9)=0 equation:

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

We multiply parentheses ..

(+4x^2+36x-2x-18)=0

We get rid of parentheses

4x^2+36x-2x-18=0

We add all the numbers together, and all the variables

4x^2+34x-18=0

a = 4; b = 34; c = -18;
Δ = b2-4ac
Δ = 342-4·4·(-18)
Δ = 1444
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1444}=38$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(34)-38}{2*4}=\frac{-72}{8}
=-9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(34)+38}{2*4}=\frac{4}{8}
=1/2
$