Step by step
The question
Question: graph y = −√x + 2 from y = √x.
We know the graph of y = √x.
It is half a U, lying on its side.
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.
Outside, at the end, + 2 adds 2 to every y.
So the graph moves up 2.
Careful!
A minus inside flips left and right.
A minus outside flips up and 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 up 2.
(0, 0) goes to (0, 2).
(1, 1) stays where it is.
(4, 2) goes to (4, 0).
4 Draw the new graph
Join the new points with the same shape, flipped.
This is y = −√x + 2.
5 Check
Let's check.
Put x = 0 in the new rule.
We get y = 2: the point (0, 2) we drew.
And x = 4 gives y = 0: the point (4, 0).
Let's look back.
First: read the changes.
Then: start from y = √x.
Then: move the points.
Then: draw the new graph.
Last: check.