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Graph y = 1/2|x| from y = |x|

Step by step, with the reason for every step · Graph stretches · Algebra 2

Step by step

The question

Question: graph y = one half times |x|, from y = |x|.

y = 12|x|

We know the graph of y = |x|.

It is a V.

we know: y = |x|

1 Read the changes

The one half in front makes every y one half as big.

Smaller y's: the graph gets wider and flatter.

12 in front → every y × 12

Careful!

A number bigger than 1 makes it narrower.

A number between 0 and 1 makes it wider.

Careful: a number between 0 and 1 in front: wider, not narrower

2 Start from y = |x|

Draw the grid.

Draw y = |x| first.

It goes through (−2, 2), (0, 0) and (2, 2).

3 Shrink the y's

(−2, 2): one half of 2 is 1.

It goes to (−2, 1).

(0, 0) stays: one half of 0 is 0.

(2, 2): one half of 2 is 1.

It goes to (2, 1).

4 Draw the new graph

Join them with the same shape, wider.

This is the new graph.

5 Check

Let's check: put x = 2 in the new rule.

One half of 2 is 1.

We get the point (2, 1).

It works!

x = 2: y = 12|2| = 12 × 2 = 1

Let's look back.

First: read the changes.

Then: start from y = |x|.

Then: shrink the y's.

Then: draw the new graph.

Last: check.

Answer
12 in front → every y × 12

Your turn

Try this one yourself, then check:

graph y = 13|x| from y = |x|
Show the answer
corner (0, 0), through (3, 1)

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