# Problem with “Calculated Formula” question in blackboard online test

I received the error message "Question Syntax. There is an error in the syntax of this question. One or more variables may be invalid." when I tried to make the following question:

Compute $\|\langle [x], [y], [z] \rangle \times \langle [u], [v], [w] \rangle \|$.

$\sqrt{(y \times w - z \times v)^2 + (z \times u - x \times w)^2 + (x \times v - y \times u)^2}$.

Can anyone help me, please ?

EDIT: I am using the "blackboard learn" course management software. I am a teacher, making an online quiz for my students.

• It is impossible to answer the question because the notation used in posing it is not defined. – Dan Fox Nov 13 '16 at 10:06
• The square brackets are required by the automatic answer calculation code in blackboard, to identify x, y, z, u, v and w as variables. I intended them to be real numbers. In the question, the automated system is not required to understand the mathematics, only to understand which are the variables. In the answer formula, I intend the 'x' symbol to mean multiplication of real numbers. – Simon Nov 13 '16 at 10:08
• Blackboard is a course management tool used in many Universities: en.m.wikipedia.org/wiki/Blackboard_Learn. Those who are unfamiliar with it will of course be unable to answer my question. I had hoped that some users of this forum might have experience with it. Although you don't know it, in case there might be some users who do know it, I would ask that you please not vote to close my question. I am indeed a teacher trying to create a question, as I hoped I had conveyed by writing "...when I tried to make the following question...". Apologies if I was not clear. – Simon Nov 13 '16 at 14:07
• I apologize that I misunderstood you. I've retracted my close vote. I suggest that you edit your post to include the details you've put as comments. – Joel Reyes Noche Nov 13 '16 at 14:23
• Just to make sure I am understanding the question: is the X symbol you are using to denote multiplication of scalars the symbol that Blackboard wants you to use, or just one you are choosing here for clarity of presentation? – mweiss Jan 25 '17 at 19:57