3(4x+7)=4x-25)7x+15=3(3x-7)

Solution for 3(4x+7)=4x-25)7x+15=3(3x-7) equation:

3(4x+7)=4x-25)7x+15=3(3x-7)

We move all terms to the left:

3(4x+7)-(4x-25)7x+15)=0

We add all the numbers together, and all the variables

3(4x+7)-(4x-25)7x=0

We multiply parentheses

-28x^2+12x+175x+21=0

We add all the numbers together, and all the variables

-28x^2+187x+21=0

a = -28; b = 187; c = +21;
Δ = b2-4ac
Δ = 1872-4·(-28)·21
Δ = 37321
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(187)-\sqrt{37321}}{2*-28}=\frac{-187-\sqrt{37321}}{-56}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(187)+\sqrt{37321}}{2*-28}=\frac{-187+\sqrt{37321}}{-56}
$