5x(3+7x)=0

Solution for 5x(3+7x)=0 equation:

5x(3+7x)=0

We add all the numbers together, and all the variables

5x(7x+3)=0

We multiply parentheses

35x^2+15x=0

a = 35; b = 15; c = 0;
Δ = b2-4ac
Δ = 152-4·35·0
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-15}{2*35}=\frac{-30}{70}
=-3/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+15}{2*35}=\frac{0}{70}
=0
$