(2x-1)*(4x+5)=0

Solution for (2x-1)*(4x+5)=0 equation:

(2x-1)(4x+5)=0

We multiply parentheses ..

(+8x^2+10x-4x-5)=0

We get rid of parentheses

8x^2+10x-4x-5=0

We add all the numbers together, and all the variables

8x^2+6x-5=0

a = 8; b = 6; c = -5;
Δ = b2-4ac
Δ = 62-4·8·(-5)
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-14}{2*8}=\frac{-20}{16}
=-1+1/4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+14}{2*8}=\frac{8}{16}
=1/2
$