Vector - points in same direction

AI Thread Summary
The discussion revolves around determining which options point in the same direction as the vector V = (-sqrt2, sqrt3, sqrt5). Participants highlight the importance of understanding that any positive scalar multiple of a vector will point in the same direction. The user expresses uncertainty about how to represent vectors and square roots in the forum format. The community encourages a focus on vector properties rather than providing direct answers, emphasizing the need for clarity in mathematical expressions. Overall, the conversation aims to guide the user toward understanding vector directionality and proper notation.
marionca57
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I don't know how to make the vector arrow on top of the letter so I just underlined the vectors. Also I don't know how to make the square root symbol so I just type sqrt for it.

Homework Statement


Which points in the same direction as V = (-sqrt2, sqrt3, sqrt5)
a) 1/10 V
b) sqrt10/10 V
c) sqrt10 V
d) sqrt 10 V


Homework Equations





The Attempt at a Solution


I am not sure where to start other than calulating the sqrt of 2,3, and 5. My best guess would be c but I need to know why if that is correct or some help figuring it out.
Please help,
Thanks,
Marion
 
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Welcome to PF!

marionca57 said:
I don't know how to make the vector arrow on top of the letter so I just underlined the vectors. Also I don't know how to make the square root symbol so I just type sqrt for it.

Hi Marion! Welcome to PF! :smile:

(have a square-root: √ :smile:)

On this forum, type vectors in bold. :wink:
Which points in the same direction as V = (-sqrt2, sqrt3, sqrt5)
a) 1/10 V
b) sqrt10/10 V
c) sqrt10 V
d) sqrt 10 V

I am not sure where to start other than calulating the sqrt of 2,3, and 5. My best guess would be c but I need to know why if that is correct or some help figuring it out.

(c and d look the same :confused:)

As you probably know, on this forum we don't tell you the answer, we just try to nudge you in the right direction. :wink:

What tests do you know for two vectors to be pointing in the same direction? :smile:
 
It is a good idea to make carefull use of parentheses so that there is no
ambiguity as to the meaning of an expression.

Consider that for positive constants k, and vectors v, k v is in the same direction of v.
 
I tried to combine those 2 formulas but it didn't work. I tried using another case where there are 2 red balls and 2 blue balls only so when combining the formula I got ##\frac{(4-1)!}{2!2!}=\frac{3}{2}## which does not make sense. Is there any formula to calculate cyclic permutation of identical objects or I have to do it by listing all the possibilities? Thanks
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks
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