-28+7x=-7x(8+x)

Solution for -28+7x=-7x(8+x) equation:

-28+7x=-7x(8+x)

We move all terms to the left:

-28+7x-(-7x(8+x))=0

We add all the numbers together, and all the variables

7x-(-7x(x+8))-28=0


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

-7x(x+8)

We multiply parentheses

-7x^2-56x

Back to the equation:

-(-7x^2-56x)


We get rid of parentheses

7x^2+56x+7x-28=0

We add all the numbers together, and all the variables

7x^2+63x-28=0

a = 7; b = 63; c = -28;
Δ = b2-4ac
Δ = 632-4·7·(-28)
Δ = 4753
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{4753}=\sqrt{49*97}=\sqrt{49}*\sqrt{97}=7\sqrt{97}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(63)-7\sqrt{97}}{2*7}=\frac{-63-7\sqrt{97}}{14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(63)+7\sqrt{97}}{2*7}=\frac{-63+7\sqrt{97}}{14}
$