Steply

v = <2, 1>, find 3v

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

Step by step

The question

Question: find 3v, when v = ⟨2, 1⟩.

v = ⟨2, 1⟩

1 Draw the arrows

Draw the grid.

Draw v = ⟨2, 1⟩ from the origin.

3v means 3 times v: 3 arrows v, tip to tail.

Together they make one arrow, 3 times as long.

That is 3v.

2 Multiply each part

3v means: multiply each part of v by 3.

3v = ⟨3 × 2, 3 × 1⟩

Careful!

Both parts are multiplied, not only the first one.

The arrow gets longer across and up.

Careful: not ⟨6, 1⟩ ✗

3 times 2 is 6.

3 times 1 is 3.

So 3v = ⟨6, 3⟩.

3v = ⟨6, 3⟩

3 Check

Let's check on the grid.

The red arrow ends at (6, 3).

That is right 6 and up 3 from the start: ⟨6, 3⟩.

The same!

tip (6, 3) → ⟨6, 3⟩

Let's look back.

First: draw the arrows.

Then: multiply each part.

Last: check.

Answer
3v = ⟨6, 3⟩

Your turn

Try this one yourself, then check:

v = ⟨1, 1⟩: find 3v
Show the answer
3v = ⟨3, 3⟩

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