(2m-5)(4m+11)=0

Solution for (2m-5)(4m+11)=0 equation:

(2m-5)(4m+11)=0

We multiply parentheses ..

(+8m^2+22m-20m-55)=0

We get rid of parentheses

8m^2+22m-20m-55=0

We add all the numbers together, and all the variables

8m^2+2m-55=0

a = 8; b = 2; c = -55;
Δ = b2-4ac
Δ = 22-4·8·(-55)
Δ = 1764
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1764}=42$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-42}{2*8}=\frac{-44}{16}
=-2+3/4
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+42}{2*8}=\frac{40}{16}
=2+1/2
$