A=(20-2w)w

Solution for A=(20-2w)w equation:

=(20-2A)A

We move all terms to the left:

-((20-2A)A)=0

We add all the numbers together, and all the variables

-((-2A+20)A)=0


We calculate terms in parentheses: -((-2A+20)A), so:

(-2A+20)A

We multiply parentheses

-2A^2+20A

Back to the equation:

-(-2A^2+20A)


We get rid of parentheses

2A^2-20A=0

a = 2; b = -20; c = 0;
Δ = b2-4ac
Δ = -202-4·2·0
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-20}{2*2}=\frac{0}{4}
=0
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+20}{2*2}=\frac{40}{4}
=10
$