A=(3x-2)(7x-4)

Solution for A=(3x-2)(7x-4) equation:

=(3A-2)(7A-4)

We move all terms to the left:

-((3A-2)(7A-4))=0

We multiply parentheses ..

-((+21A^2-12A-14A+8))=0


We calculate terms in parentheses: -((+21A^2-12A-14A+8)), so:

(+21A^2-12A-14A+8)

We get rid of parentheses

21A^2-12A-14A+8

We add all the numbers together, and all the variables

21A^2-26A+8

Back to the equation:

-(21A^2-26A+8)


We get rid of parentheses

-21A^2+26A-8=0

a = -21; b = 26; c = -8;
Δ = b2-4ac
Δ = 262-4·(-21)·(-8)
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(26)-2}{2*-21}=\frac{-28}{-42}
=2/3
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(26)+2}{2*-21}=\frac{-24}{-42}
=4/7
$