not quite sure how the answer is -20/9.
If 3x^2 - 2x +7 = 0 then (x-1/3)^2 =??? -20/9 but how?
You've given an expression, not an equation so x can't be solved for. At best you can say
(x - 1/3)^2 =
x^2 - 2x/3 + 1/9
x - 1/3 * x - 1/3
Polynomial multiply:
x^2 -1/3x - 1/3x +1/9
x^2 - 2/3x + 1/9
-20/9 implies you left out some information.
Comments
You've given an expression, not an equation so x can't be solved for. At best you can say
(x - 1/3)^2 =
x^2 - 2x/3 + 1/9
x - 1/3 * x - 1/3
Polynomial multiply:
x^2 -1/3x - 1/3x +1/9
x^2 - 2/3x + 1/9
-20/9 implies you left out some information.