# Reflection: y-axis

How to find the image under the reflection in the y-axis: formula, 3 examples, and their solutions.

## Formula

### Formula

The image of a point (x, y)

under the reflection in the y-axis is

(-x, y).

Change the sign of x.

## Example 1

### Example

### Solution

The image of (3, 2) is

under the reflection in the y-axis.

Then the image point is,

change the sign of x,

(-3, 2).

So (-3, 2) is the answer.

### Graph

This is the graph of (3, 2)

and its image

under the reflection in the y-axis:

(-3, 2).

## Example 2

### Example

### Solution

The image of (-4, -5) is

under the reflection in the y-axis.

Then the image point is,

change the sign of x,

(4, -5).

So (4, -5) is the answer.

### Graph

This is the graph of (-4, -5)

and its image

under the reflection in the y-axis:

(4, -5).

## Example 3

### Example

### Solution

The image of [y = 2x + 1] is

under the reflection in the y-axis.

Then the image function is,

change the sign of x,

y = 2(-x) + 1.

2(-x) = -2x

So [y = -2x + 1] is the answer.

### Graph

This is the graph of [y = 2x + 1]

and its image

under the reflection in the y-axis:

y = 2(-x) + 1.