When I had to form an equation, I got x^2-2x+11/9. Do I have to get rid of the fraction and make it to be 9x^2-18x+11=0?

Answer 1

no; fractions are perfectly acceptable. Most folks like to get rid of them, though, so the second form makes them more comfortable.

You could just as well have used any of

x^2/7 - 2x/7 + 11/63 = 0
5x^2 - 10x + 55/9 = 0
90x^2 - 180x + 110 = 0

Answer 2

Ohhh ok, thks!