Grading equations in a specific form

I am struggling to find a way to create a maple graded question, that accepts a quadratic equation, but only in a specific form. For instance,
I need one question that only accepts as correct the standard form, another one that only accepts factored form, and other that only accepts vertex form.
Maple treats all three as equivalent (because they are) but how then can I restrict a student to use a particular form?
As a side question, I seem to have better luck when the response area is only used for the RHS of the equation. Whenever I try to have a maple graded response area that includes "y=" as part of the correct answer, I get all kinds of errors. Why is this?
Any help is greatly appreciated!

Hi!
If you're comfortable with Maple programming language, you can try 'inert form'. It will allow you to grade student response in its original form, without simplifications. Click here for an example.
Alternatively, you can convert the response to "string" and use string tools to check if the expression contains (the right number of) brackets, this should allow you to identify the expression type. I'm thinking alongs the lines of: student answer is equal to the correct answer AND the number of "(" brackets is right.
With regards to "y=" part. It's hard to say without the actual grading code. You could try to pull the the equation apart with use of lhs and rhs commands. For example, "y= a + b" would give you "y" and "a+b" respectively. This should allow you to grade equation in two parts without equation comparisons.
When assigning variable names to the equations (Maple syntax) I often forget to use ":", for example: "my_equation = y = a+b" instead of "my_equation := y = a+b". This leads to similar error messages.
Good luck!
Anatoly