Science talk:Math Exam Resources/Courses/MATH152/April 2011/Question A15

the question asks us to project onto the vector with direction [1,2], not [2,1]. is there a mistake in the solution?

Good catch, it's changed now and put back to RS. Please review.

I would like to suggest that this solution is incorrect.

The formula for projection is not correct.

My fellow classmates have also suggested this as well.

Hi, how did you learn the formula for vector projection in class? Can you state more specifically what is wrong here? Is it just the denominator, which should be $\mathbf {u\cdot u} =5$ instead of Failed to parse (syntax error): {\displaystyle |\mathbf{u}| = \sqrt{5} } ?

Yes, that is correct. From Wolfram:
It should be this since we are looking for a vector result:
For the length it is:

This one seems to be a weird mix between the two:

I agree. This is fixed now. Thank you!

No worries!