# Pre-Calc

posted by .

Can anyone help with the following problem please...Thank u so much

Let f(x) =|9x|. For the area above the x-axis and between the lines x= -9 and x=18

a. draw and label a sketch with

b. find the area of the region in
the xy-plane under the graph
of f(x)

• Pre-Calc -

For this kind of problem, it is always desirable to make a sketch within the limits of the domain, from x=-9 to 18.
See:
http://img510.imageshack.us/img510/2928/1291868155.png

Using the formula for the area of a triangle as:
Area = (1/2)base*height
You can find the areas of the two triangles between the function and the x-axis.

If you need further help, don't hesitate to post.

• Pre-Calc -

Amy, please check to see if your question has been answered before posting the same question again.

you asked the same question with only a small change yesterday,
http://www.jiskha.com/display.cgi?id=1291781963

MathMate has gone to some length to answer it again, even creating a picture for you.

make a note of your post by jotting down the time of the first posting, even though it moves off the page, it is then rather easy to find

• Pre-Calc -