-3(x+3)7x=-1

Solution for -3(x+3)7x=-1 equation:

-3(x+3)7x=-1

We move all terms to the left:

-3(x+3)7x-(-1)=0

We add all the numbers together, and all the variables

-3(x+3)7x+1=0

We multiply parentheses

-21x^2-63x+1=0

a = -21; b = -63; c = +1;
Δ = b2-4ac
Δ = -632-4·(-21)·1
Δ = 4053
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{-(-63)-\sqrt{4053}}{2*-21}=\frac{63-\sqrt{4053}}{-42}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-63)+\sqrt{4053}}{2*-21}=\frac{63+\sqrt{4053}}{-42}
$