Steply

v = <1, 3>, find 2v

Step by step, with the reason for every step · Adding, subtracting, × a number · Precalculus

Step by step

The question

Question: find 2v, when v = ⟨1, 3⟩.

v = ⟨1, 3⟩

1 Draw the arrows

Draw the grid.

Draw v = ⟨1, 3⟩ from the origin.

2v means 2 times v: 2 arrows v, tip to tail.

Together they make one arrow, 2 times as long.

That is 2v.

2 Multiply each part

2v means: multiply each part of v by 2.

2v = ⟨2 × 1, 2 × 3⟩

Careful!

Both parts are multiplied, not only the first one.

The arrow gets longer across and up.

Careful: not ⟨2, 3⟩ ✗

2 times 1 is 2.

2 times 3 is 6.

So 2v = ⟨2, 6⟩.

2v = ⟨2, 6⟩

3 Check

Let's check on the grid.

The red arrow ends at (2, 6).

That is right 2 and up 6 from the start: ⟨2, 6⟩.

The same!

tip (2, 6) → ⟨2, 6⟩

Let's look back.

First: draw the arrows.

Then: multiply each part.

Last: check.

Answer
2v = ⟨2, 6⟩

Your turn

Try this one yourself, then check:

v = ⟨1, 2⟩: find 2v
Show the answer
2v = ⟨2, 4⟩

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