(5x+10)(7x-2)=0

Solution for (5x+10)(7x-2)=0 equation:

(5x+10)(7x-2)=0

We multiply parentheses ..

(+35x^2-10x+70x-20)=0

We get rid of parentheses

35x^2-10x+70x-20=0

We add all the numbers together, and all the variables

35x^2+60x-20=0

a = 35; b = 60; c = -20;
Δ = b2-4ac
Δ = 602-4·35·(-20)
Δ = 6400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6400}=80$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(60)-80}{2*35}=\frac{-140}{70}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(60)+80}{2*35}=\frac{20}{70}
=2/7
$