(x+4)(7x+7)=0

Solution for (x+4)(7x+7)=0 equation:

(x+4)(7x+7)=0

We multiply parentheses ..

(+7x^2+7x+28x+28)=0

We get rid of parentheses

7x^2+7x+28x+28=0

We add all the numbers together, and all the variables

7x^2+35x+28=0

a = 7; b = 35; c = +28;
Δ = b2-4ac
Δ = 352-4·7·28
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(35)-21}{2*7}=\frac{-56}{14}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(35)+21}{2*7}=\frac{-14}{14}
=-1
$