A=-7a(2a-8)

Solution for A=-7a(2a-8) equation:

=-7A(2A-8)

We move all terms to the left:

-(-7A(2A-8))=0


We calculate terms in parentheses: -(-7A(2A-8)), so:

-7A(2A-8)

We multiply parentheses

-14A^2+56A

Back to the equation:

-(-14A^2+56A)


We get rid of parentheses

14A^2-56A=0

a = 14; b = -56; c = 0;
Δ = b2-4ac
Δ = -562-4·14·0
Δ = 3136
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3136}=56$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-56)-56}{2*14}=\frac{0}{28}
=0
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-56)+56}{2*14}=\frac{112}{28}
=4
$