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# C4 question watch

1. "The vector equation of the line through the point A(2,3) in the direction of the vector 2i+4j can be written as?"
I got y=2x-1 but not sure if it is right or not.
How would you solve this type of question asking for equation of a vector like this? (i.e: parrallel or in the same direction)
Thanks
2. (Original post by prepdream)
"The vector equation of the line through the point A(2,3) in the direction of the vector 2i+4j can be written as?"
I got y=2x-1 but not sure if it is right or not.
How would you solve this type of question asking for equation of a vector like this? (i.e: parrallel or in the same direction)
Thanks
Does the question specific whether you need to write the vector equation or Cartesian equation down?
3. (Original post by B_9710)
Does the question specific whether you need to write the vector equation or Cartesian equation down?
No, just vector equation in general so I think both is fine
4. (Original post by prepdream)
"The vector equation of the line through the point A(2,3) in the direction of the vector 2i+4j can be written as?"
I got y=2x-1 but not sure if it is right or not.
How would you solve this type of question asking for equation of a vector like this? (i.e: parrallel or in the same direction)
Thanks
If line contains the point with position vector and is parallel to then you can write it as
5. (Original post by Zacken)
If line contains the point with position vector and is parallel to then you can write it as
Thanks. What about the type of question about "in the direction of...", how would you solve it?
6. (Original post by prepdream)
"The vector equation of the line through the point A(2,3) in the direction of the vector 2i+4j can be written as?"
I got y=2x-1 but not sure if it is right or not. Correct
How would you solve this type of question asking for equation of a vector like this? (i.e: parrallel or in the same direction)
Thanks
If you mean working backwards, ie starting with y = 2x - 1, then:

You know the gradient is 2, and a point on the line is x=2, y = 3 (by plugging them into the above).

Now, r = (2,3) + λ(2,1)
7. (Original post by Bath_Student)
If you mean working backwards, ie starting with y = 2x - 1, then:

You know the gradient is 2, and a point on the line is x=2, y = 3 (by plugging them into the above).

Now, r = (2,3) + λ(2,1)
OP, ignore this - it's wrong.
8. (Original post by prepdream)
Thanks. What about the type of question about "in the direction of...", how would you solve it?
"in the direction of..." = parallel to, so same thing. If it's in the direction of and contains then you can write it as

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