9.8=x(8-x)

Solution for 9.8=x(8-x) equation:

9.8=x(8-x)

We move all terms to the left:

9.8-(x(8-x))=0

We add all the numbers together, and all the variables

-(x(-1x+8))+9.8=0


We calculate terms in parentheses: -(x(-1x+8)), so:

x(-1x+8)

We multiply parentheses

-1x^2+8x

Back to the equation:

-(-1x^2+8x)


We get rid of parentheses

1x^2-8x+9.8=0

We add all the numbers together, and all the variables

x^2-8x+9.8=0

a = 1; b = -8; c = +9.8;
Δ = b2-4ac
Δ = -82-4·1·9.8
Δ = 24.8
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-\sqrt{24.8}}{2*1}=\frac{8-\sqrt{24.8}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+\sqrt{24.8}}{2*1}=\frac{8+\sqrt{24.8}}{2}
$