A=-(7y)(8-10y)

Solution for A=-(7y)(8-10y) equation:

=-(7A)(8-10A)

We move all terms to the left:

-(-(7A)(8-10A))=0

We add all the numbers together, and all the variables

-(-7A(-10A+8))=0


We calculate terms in parentheses: -(-7A(-10A+8)), so:

-7A(-10A+8)

We multiply parentheses

70A^2-56A

Back to the equation:

-(70A^2-56A)


We get rid of parentheses

-70A^2+56A=0

a = -70; b = 56; c = 0;
Δ = b2-4ac
Δ = 562-4·(-70)·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*-70}=\frac{-112}{-140}
=4/5
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(56)+56}{2*-70}=\frac{0}{-140}
=0
$