# Math Help - evaluate given vectors

1. ## evaluate given vectors

Please can someone help with this? I've been having a lot of problems with this. And if you could explain it an not just give me the answer, I'm trying to actually learn how to do this. Thank you for any help you can provide.

Evaluate the expression:

v ⋅ w

Given the vectors:

r = <8, 8, -6>; v = <3, -8, -3>; w = <-4, -2, -6>

2. ## Re: evaluate given vectors

Originally Posted by Itel
Please can someone help with this? I've been having a lot of problems with this. And if you could explain it an not just give me the answer, I'm trying to actually learn how to do this. Thank you for any help you can provide.
Evaluate the expression:
v ⋅ w
Given the vectors:
r = <8, 8, -6>; v = <3, -8, -3>; w = <-4, -2, -6>

$\cdot=ax+by+cz$.

Would it be
8*3
8*-8
-6*-3?

4. ## Re: evaluate given vectors

Originally Posted by Itel
Would it be
8*3
8*-8
-6*-3?
NO INDEED.

Apply the rule that I posted.

5. ## Re: evaluate given vectors

Which is 24+-64+18=-22?

6. ## Re: evaluate given vectors

Originally Posted by Itel
Which is 24+-64+18=-22?
Which is correct. The dot product gives a number.
Because it is negative tells us that the angle between the vectors is obtuse.

7. ## Re: evaluate given vectors

So that's the answer? -22 and its obtuse?

8. ## Re: evaluate given vectors

are you taking an online course?

9. ## Re: evaluate given vectors

No. I'm in college.

10. ## Re: evaluate given vectors

Originally Posted by Itel
No. I'm in college.
REALLY? What in the world is that college is using as a textbook?
Please name both college and textbook, as well as the course name.

I find all your posts unbelievable coming from a college student studying anything to do with vectors.

11. ## Re: evaluate given vectors

Evaluate the expression:

v ⋅ w

Given the vectors:

r = <8, 8, -6>; v = <3, -8, -3>; w = <-4, -2, -6>
${\color{red}v \cdot w} = (3)(-4) + (-8)(-2) + (-3)(-6) = -12 + 16 + 18 = 22$

vector r = <8,8,-6> has no affect on the dot product of vectors v and w

12. ## Re: evaluate given vectors

What you don't believe me? :P

West Georgia Technical College
Math 1131 (which is calculus)
ISBN 978-1-133-22867-7 or 1-133-22867-4 (I don't which one is which)