Drexel dragonThe Math ForumDonate to the Math Forum

Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.

Math Forum » Discussions » Education » math-teach

Topic: MIT Math Diagnostic for Physics Placement
Replies: 17   Last Post: Oct 24, 2012 12:51 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Dave L. Renfro

Posts: 4,791
Registered: 12/3/04
Re: MIT Math Diagnostic for Physics Placement
Posted: Oct 23, 2012 10:32 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Dave L. Renfro wrote (in part):


>> Problem B2: Instead of saying "Find all possible values of x which
>> solve the equation x^4 - 13x^2 + 36 = 0", I would be less vague and
>> explicitly ask for all complex solutions.

Robert Hansen wrote (in part):


> Doesn't that factor to (x^2 - 9)(x^2 - 4)? -> x = +/-3, +/-2

Using "complex solutions" gives test takers making certain
kinds of errors more rope to hang themselves with, although
personally I consider something like x = +/- 3i, +/- 2i to
be better than something like x = +/-9, +/-4, which in turn
is better than something like x = +/-13, +/-36. Ideally, I'd
want to see their work, but in the absence of that, for a
total of 5 points for this problem, I might give 3 points
for x = +/- 3i, +/- 2i and 1-2 points for x = +/-9, +/-4.
Note that even x = +/-9, +/-4 suggests they correctly factored
and they recognized there will be two pairs of solutions.

Dave L. Renfro

Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© The Math Forum 1994-2015. All Rights Reserved.