Math Help

Archive for December, 2006

Question: I don’t understand average rate of change. AT ALL! (9th grade math)?

I’m taking an online class, and I don’t understand it at all. (9th grade math) Average Rate of Change is confusing. I don’t understand the concept, or how to do ANYTHING with average rate of change.

I have to turn this in my wednesday, so PLEASE HELP! She gives us video’s and a few things, but the review is not like the assignment.

How do you determine the average rate of change from a graph? How do you calculate avg. roc from a set of points or a table? How can equations be written in slope intercept form.

Answer: hi, so say for example, the avg rate of change is meters/second
your graph would be distance vs time
to get the avg rate of change, it is the same as the slope of the graph which is rise/run —> (y2-y1)/(x2-x1) which are two points
this is the same for points in a table, you find two points and calculate the slope using the formula above
I am guessing that since its grade 9 math, the line would be a straight line anyways, but pick another pair of points to make sure that the slope is constant through out when it is in a table form (if its in graph, its probably a straight line, or you construct a line of best fit?)

slope intercept form is y=mx+b
where m is the slope and b is the y=intercept
basically, to write it in y=mx+b form, you isolate for y ^^
hope this helps

Math Help : How to Calculate an Average

Below are formulas for binomial expansion. Binomial expansion is very useful in math and can be applied to many real life situations.

For positive integers n ()

Another useful binomial expansion is:

for

Question: Please Help With Math area problem?

Express the area of a rectangular field whose perimeter is 320 meters as a function of the length of one of its sides. Estimate the dimensions of the field of maximum area.

Answer: Let L = length and W = width.
2L + 2W = 320, so L = 160 – W
Area = L * W = (160 – W) * W = 160W – W^2
Set the derivative equal to zero.
160 – 2W = 0
W = 80, L = 80, Area = 6400 sq m

Surface Area – YourTeacher.com – Math Help