A=3x(2x+8)

Solution for A=3x(2x+8) equation:

=3A(2A+8)

We move all terms to the left:

-(3A(2A+8))=0


We calculate terms in parentheses: -(3A(2A+8)), so:

3A(2A+8)

We multiply parentheses

6A^2+24A

Back to the equation:

-(6A^2+24A)


We get rid of parentheses

-6A^2-24A=0

a = -6; b = -24; c = 0;
Δ = b2-4ac
Δ = -242-4·(-6)·0
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-24)-24}{2*-6}=\frac{0}{-12}
=0
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-24)+24}{2*-6}=\frac{48}{-12}
=-4
$