# Math Help - functions...help?

1. ## functions...help?

Use a graphing calculator to graph the function and visually determine the intervals on which the function is increasing, decreasing, or constant.

f(x)= 4x, x<2
f(x)= 8, 2<x<6
f(x)= -1/2x+11, x>6

I think my biggest problem with this question...is that I don't understand the question. I have never had a problem like this before and am not sure how to graph this with my calculator or what is meant by visually determining the intervals...Help, please?

2. Originally Posted by iheartthemusic29
Use a graphing calculator to graph the function and visually determine the intervals on which the function is increasing, decreasing, or constant.

f(x)= 4x, x<2
f(x)= 8, 2<x<6
f(x)= -1/2x+11, x>6

I think my biggest problem with this question...is that I don't understand the question. I have never had a problem like this before and am not sure how to graph this with my calculator or what is meant by visually determining the intervals...Help, please?
Hello,

you have to examine a piecewise defined function:

$f(x)=\left\{\begin{array}{cc}4x,& x \leq 2 \\8, & 2 < x \leq 6 \\ -\frac{1}{2}x + 11, & x > 6 \end{array}\right.$

I'm going to show you how to type this function into your calculator:
1. Open the $\boxed{y=}$ editor. Go to y1= and press F3

2. Pick from the catalog the command when(

3. The complete input line looks like this:

y1= when(x ≤ 6, when(x ≤ 2, 4x,8),-1/2*x+11)

You get the sign ≤ by typing <=. Your calculator transform these two signs into one sign.

4. Open the $\boxed{\text{WINDOW}}$ editor. Use the following settings:
xmin = -2
xmax = 10
xscl = 1
ymin = -2
ymax = 10
yscl = 1
xres = 3

I've attached 2 screenshots:
1. The input screen
2. The graph of the function