Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

There is not an example problem in my textbook that I can reference (I have said this on two other questions so far, but it's the truth. The example problems and solutions manual contain physics / engineering examples rather than abstract examples).

For this one, I did not know how to begin. Normally I would give the work I had done, even if it is incorrect.

For what values of t and so does the equality <4-2t, 2s-4t >= < s+4t, 3+2t>. Find t and s. At these values of t and s, find the resulting vector.

Can anyone point me in the correct direction or give me an idea on how to solve this?

Thank you in advance.

share|cite|improve this question
I would say that the correct direction is towards the library, to find a decent linear algebra textbook (since the one you have doesn't seem to be of much use to you). ;) – Hans Lundmark Jan 27 '11 at 6:52

Set the $x$-components equal to each other and the $y$-components equal to each other.

share|cite|improve this answer

Two vectors are equal if and only if they are identical: the first component of each should be equal, the second component of each should be equal. So for the vectors $\langle 4-2t, 2s-4t\rangle$ and $\langle s+4t, 3+2t\rangle$ to be equal, you must have $4-2t = s+4t$ (first components equal) and $2s-4t = 3+2t$ (second components equal). This is a system of two equations in two unknowns; solve them to find (all) value(s) of $s$ and $t$ that make the equality true. Then plug the values to get the "resulting vector"(s).

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.