(8+x)(1+5x)=0

Solution for (8+x)(1+5x)=0 equation:

(8+x)(1+5x)=0

We add all the numbers together, and all the variables

(x+8)(5x+1)=0

We multiply parentheses ..

(+5x^2+x+40x+8)=0

We get rid of parentheses

5x^2+x+40x+8=0

We add all the numbers together, and all the variables

5x^2+41x+8=0

a = 5; b = 41; c = +8;
Δ = b2-4ac
Δ = 412-4·5·8
Δ = 1521
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1521}=39$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(41)-39}{2*5}=\frac{-80}{10}
=-8
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(41)+39}{2*5}=\frac{-2}{10}
=-1/5
$