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

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

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

We multiply parentheses ..

-(+10x^2+2x+25x+5)=0

We get rid of parentheses

-10x^2-2x-25x-5=0

We add all the numbers together, and all the variables

-10x^2-27x-5=0

a = -10; b = -27; c = -5;
Δ = b2-4ac
Δ = -272-4·(-10)·(-5)
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{-(-27)-23}{2*-10}=\frac{4}{-20}
=-1/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-27)+23}{2*-10}=\frac{50}{-20}
=-2+1/2
$