3x(5x+7)=3x(5-7x)

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

3x(5x+7)=3x(5-7x)

We move all terms to the left:

3x(5x+7)-(3x(5-7x))=0

We add all the numbers together, and all the variables

3x(5x+7)-(3x(-7x+5))=0

We multiply parentheses

15x^2+21x-(3x(-7x+5))=0


We calculate terms in parentheses: -(3x(-7x+5)), so:

3x(-7x+5)

We multiply parentheses

-21x^2+15x

Back to the equation:

-(-21x^2+15x)


We get rid of parentheses

15x^2+21x^2-15x+21x=0

We add all the numbers together, and all the variables

36x^2+6x=0

a = 36; b = 6; c = 0;
Δ = b2-4ac
Δ = 62-4·36·0
Δ = 36
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36}=6$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-6}{2*36}=\frac{-12}{72}
=-1/6
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+6}{2*36}=\frac{0}{72}
=0
$