- #1
1MileCrash
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- 41
Homework Statement
Hey guys, I have two separate questions.
1.)
I am asked for a unit vector pointing from P = (1,2) to Q = (4,6)
In physics, every vector I've ever worked with started at the origin, so these feel weird.
I initially thought that it would simply be 3i + 4j, the differences of each coordinate. However, my book gives the answer as (3/5)i + (4/5)j, they divided each number by sqrt(3^2 + 4^2). But why? Why specifically divide by that? If I understand correctly, if you divide both numbers by anyone number, the vector will still point the same way because you just make a similar triangle. Why divide by vector length?
2.)
Limits and Continuity has been very confusing for me.
I am asked to show that f(x,y) does not have a limit as (x,y) -> (0,0), and it says (Hint: use the line y = mx)
The function is (x^2 - y^2)/(x^2 + y^2). How do I use y = mx?
Homework Equations
The Attempt at a Solution
Looking for more of a explanation to help me better understand, not a solution.