A=(2x+x+1)(x-1)

Solution for A=(2x+x+1)(x-1) equation:

=(2A+A+1)(A-1)

We move all terms to the left:

-((2A+A+1)(A-1))=0

We add all the numbers together, and all the variables

-((3A+1)(A-1))=0

We multiply parentheses ..

-((+3A^2-3A+A-1))=0


We calculate terms in parentheses: -((+3A^2-3A+A-1)), so:

(+3A^2-3A+A-1)

We get rid of parentheses

3A^2-3A+A-1

We add all the numbers together, and all the variables

3A^2-2A-1

Back to the equation:

-(3A^2-2A-1)


We get rid of parentheses

-3A^2+2A+1=0

a = -3; b = 2; c = +1;
Δ = b2-4ac
Δ = 22-4·(-3)·1
Δ = 16
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16}=4$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-4}{2*-3}=\frac{-6}{-6}
=1
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+4}{2*-3}=\frac{2}{-6}
=-1/3
$