Babynini one year ago Vectors, please check :)

1. Babynini

A few simple questions! u= <-2,4> v=5i-3i 1) find 6u-v = <-17,21> 2) fine a unit vector in the direction of v this one i'm ont sure about 3) graph u, v, and u-v with initial points of origin. again, i have an idea but im not sure

2. ganeshie8

look there is a typo  v=5i-3i 

3. Babynini

sowire v= 5i-3j

4. ganeshie8

6*4 - (-3) = ?

5. Babynini

27

6. Babynini

why those numbers?

7. ganeshie8

u= <-2, 4> v=5i-3j = <5, -3> 6u - v = ?

8. Babynini

<-17,21>

9. ganeshie8

can you show work for how you got 21 ?

10. Babynini

6u = <-12,24> v= <5,-3> (-12-5), (24-3) = <-17,21>

11. ganeshie8

check again

12. ganeshie8

is it 24-3 or 24-(-3) ?

13. Babynini

ooh right rigt.

14. Babynini

soo.. <-17,25> ?

15. Babynini

lol sorry, *27

16. ganeshie8

yes

17. Babynini

fabulous :)

18. Babynini

part b then

19. ganeshie8

what do u know about unit vector ?

20. Babynini

er, is this where I use cos and sin?

21. Babynini

or multiplying by scalar?

22. Babynini

Idk :/

23. Babynini

It's the angle formed by the vector and x.

24. ganeshie8

unit vector is just a vector whose magnitude is 1 and points in the same direction

25. ganeshie8

what is the magnitude of vector v ?

26. Babynini

er $\sqrt{25+9}$

27. ganeshie8

yes what do you need to do to make it 1 ?

28. Babynini

What do you mean?

29. ganeshie8

what do you need to do to $$\sqrt{25+9}$$ to make it $$1$$ ?

30. ganeshie8

dividing by $$\sqrt{25+9}$$ produces $$1$$, yes ?

31. Babynini

yeah dividing it by itself

32. ganeshie8

so the unit vector is simply : $\large \dfrac{v}{\|v\|}$

33. ganeshie8

dividing the original vector by its magnitude gives the unit vector

34. Babynini

$\frac{ 5i -3j}{ \sqrt{34} }$

35. Babynini

?

36. ganeshie8

Yes thats the unit vector in the direction of $$v$$

37. Babynini

so that would be the final answer? :)

38. ganeshie8

yes

39. Babynini

yay! Part c then ^-^

40. ganeshie8

graph the vectors

41. ganeshie8

|dw:1433398194050:dw|

42. ganeshie8

To graph the vector u= <-2,4> first plot the point (-2, 4) and draw an arrow from (0,0) to (-2,4)

43. Babynini

|dw:1433398294843:dw|

44. Babynini

(-7,7) isn't on the graph :P

45. ganeshie8

|dw:1433398431757:dw|

46. ganeshie8

yeah u-v = <-7, 7> is not on this graph but i see you get how to draw the vectors

47. ganeshie8

don't forget to put arrow at the final point

48. Babynini

okies! thanks :)

49. ganeshie8

np