Graph y = -√x - 1 from y = √x Step by Step

Step by step

The question

Question: graph y = −√x − 1 from y = √x.

y = −√x − 1

We know the graph of y = √x.

It is half a U, lying on its side.

we know: y = √x

1 Read the changes

The minus in front changes the sign of every y.

Up becomes down.

So the graph flips over the x-axis.

− in front → flip over the x-axis

Outside, at the end, − 1 takes 1 away from every y.

So the graph moves down 1.

− 1 outside → down 1

Careful!

A minus inside flips left and right.

A minus outside flips up and down.

Careful: inside → left-right, outside → up-down

2 Start from y = √x

Draw the grid.

Draw y = √x first.

It goes through (0, 0), (1, 1) and (4, 2).

3 Move the points

The start point (0, 0) moves down 1.

(0, 0) goes to (0, −1).

(1, 1) goes to (1, −2).

(4, 2) goes to (4, −3).

4 Draw the new graph

Join the new points with the same shape, flipped.

This is y = −√x − 1.

5 Check

Let's check.

Put x = 0 in the new rule.

We get y = −1: the point (0, −1) we drew.

x = 0: y = −√0 − 1 = 0 − 1 = −1

And x = 4 gives y = −3: the point (4, −3).

x = 4: y = −√4 − 1 = −2 − 1 = −3

Let's look back.

First: read the changes.

Then: start from y = √x.

Then: move the points.

Then: draw the new graph.

Last: check.

Answer