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

Solution for (1-2x)(x+4)=0 equation:

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

(-2x^2-8x+x+4)=0

We get rid of parentheses

-2x^2-8x+x+4=0

We add all the numbers together, and all the variables

-2x^2-7x+4=0

a = -2; b = -7; c = +4;
Δ = b2-4ac
Δ = -72-4·(-2)·4
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-9}{2*-2}=\frac{-2}{-4}
=1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+9}{2*-2}=\frac{16}{-4}
=-4
$