Determine values of m&n such that vector v(m-2, m+n, -2m+n) & w(2,4,-6) have same direction.

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rcmath's profile pic

rcmath | High School Teacher | (Level 1) Associate Educator

Posted on

Given that the two vectors are in the same direction does not necessary mean they have the same magnitude.

So suppose v=kw. we obtain:
m-2=2k
m+n=4k
-2m+n=-6k

Now we need to solve the system of equations:
If we substitue m=2+2k in the other two equations we obtain:
2+2k+n=4k and -2(2+2k)+n=-6k

Using the distubitive property and rearranging the terms we obtain:
n-4k=-2
n+2k=4

Subtracting the two equations we get:
-6k=-6 thus k=1.

So we can conclude that `m-2=2->m=4`

`m+n=4 -> n=4-4=0`

To confirm we use the third component `-2m+n=-2*4+0=-8!=-6`

Thus this problem does not have a solution.

 

Top Answer

jeew-m's profile pic

jeew-m | College Teacher | (Level 1) Educator Emeritus

Posted on

It is given that these vectors are in same direction.

So we take O(0,0,0) as reference.

Then direction of VO = direction of WO

 

`m-2-0 = 2-0`

`m = 4,`

 

`m+n-0 = 4-0`

`n = 4-4`

`n =0`

 

So m = 4 and n = 0 

fushi's profile pic

fushi | (Level 1) Valedictorian

Posted on

It is given that these vectors are in same direction.

So we take O(0,0,0) as reference.

Then direction of VO = direction of WO

 

 

 

So m = 4 and n = 0 

The answer is m=5 and n= 1, so the approach you took seems good, but the result is false.

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