(x+7)(8x+1)=0

Solution for (x+7)(8x+1)=0 equation:

(x+7)(8x+1)=0

We multiply parentheses ..

(+8x^2+x+56x+7)=0

We get rid of parentheses

8x^2+x+56x+7=0

We add all the numbers together, and all the variables

8x^2+57x+7=0

a = 8; b = 57; c = +7;
Δ = b2-4ac
Δ = 572-4·8·7
Δ = 3025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3025}=55$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(57)-55}{2*8}=\frac{-112}{16}
=-7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(57)+55}{2*8}=\frac{-2}{16}
=-1/8
$