(5p+4)(p+7)=0

Solution for (5p+4)(p+7)=0 equation:

(5p+4)(p+7)=0

We multiply parentheses ..

(+5p^2+35p+4p+28)=0

We get rid of parentheses

5p^2+35p+4p+28=0

We add all the numbers together, and all the variables

5p^2+39p+28=0

a = 5; b = 39; c = +28;
Δ = b2-4ac
Δ = 392-4·5·28
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$p_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$p_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$p_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(39)-31}{2*5}=\frac{-70}{10}
=-7
$
$p_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(39)+31}{2*5}=\frac{-8}{10}
=-4/5
$