3x+1=(x-1)(x+2)

Solution for 3x+1=(x-1)(x+2) equation:

3x+1=(x-1)(x+2)

We move all terms to the left:

3x+1-((x-1)(x+2))=0

We multiply parentheses ..

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


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

(+x^2+2x-1x-2)

We get rid of parentheses

x^2+2x-1x-2

We add all the numbers together, and all the variables

x^2+x-2

Back to the equation:

-(x^2+x-2)


We add all the numbers together, and all the variables

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

We get rid of parentheses

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

We add all the numbers together, and all the variables

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

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

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