Graphing Functions

Graphing Functions

• You know that in a function, every x you pick should have only one y paired with it.

DOMAIN:

5

2 5

f(x)

Range:

25 25 = x22+ 20

Okay, it IS a function !!!

We also learned how to write a function table.

x

f(x) = 2x + 1

0 f(0) = 2(0) + 1 1 f(1) = 2(1) + 1 -1

f(-1) = 2(-1) + 1

y 1 3 -1

Every function has a GRAPH that goes with it. …kinda like a portrait …

Here is a picture of y=x+1

y = 2x

y = 0x + 4

• Get ordered pairs you find on the function table….

x

f(x) = 2x + 1

0 f(0) = 2(0) + 1 1 f(1) = 2(1) + 1 -1

f(-1) = 2(-1) + 1

y 1 3 -1

(0,1) (1,3) (-1,-1)

…graph them, and connect the (0,1) dots!

(1,3) (-1,-1)

GRAPH THEM…

DRAW A LINE THROUGH THE POINTS !!

•

Try to graph these:

3. y = x + 4 4. y = 2x – 1 5. y = x² Which one is NOT a straight line?

8 4x + y=

Any function where the X and the Y don’t have any exponents is a linear function. because it’s graph makes a straight line.

y

=

x

Any function where the X or Y has an exponent, or is being square rooted, is called a nonlinear function..

y = x²

y=√x

To use the chart, you have to get y by itself in an equation.

3x + y = 14 +(-3x) +(-3x)

y = 14 + (-3x)

Another way to graph a function is to find out where the line crosses the axis.

These are called intercepts

x-intercept

y-intercept

What are the coordinates of the x &y intercepts?

(-4,0)

(0,4)

You can find the x-intercept of any function by subbing in a zero for the y, and solving it.

You can find the y-intercept by subbing in a zero for the x, and solving it.