Sunday, January 14, 2007
posted by Jhonaleen at 6:54 p.m.
On Friday's math class, we went through three things, graphing data, direct variation and Go For Gold.

Graphing Data
Ms. Armstrong took the guesswork out of deciding which information from a table of values is the dependent variable, and which is the independent variable. Even though we know that the dependent variable "relies" on the independent variable (eg. time and speed ; in this case, time would be the independent variable since the speed depends on the time that has elapsed), we learned that the first column of a table of values is always the independent variable.

Direct Variation
Definition:
A relationship between two variables in which one is a constant multiple of the other. In particular, when one variable changes the other changes in proportion to the first.

When two variable quantities have the the same ratio, they have what is called direct variation.
(This is the diagram/example we were given.)

So, in the diagram, ' p= 8h ', making it a linear function, since it's the same as ' y = mx+b ' but in
' p = 8h ' b = 0 This means that whenever b = 0, you have direct variation.
We were given other examples, too.

p = 6t + 2 <-- NOT direct variation y = 3x <-- direct variation y = -2x + 0 <-- direct variation To connect the previous lesson with this one, it is possible to write, what is called, a direct variation function. How? y = kx *In this equation, 'k' stands for 'constant' We were asked to write an equation for the following statement: The cost of selling items at \$0.25 varies directly with the number of items sold.
c -> cost n -> number of items sold
c varies directly with n (this means that the cost is always determined by how many items are sold)
So, the equation would be: c = 0.25n

Exercise 46 #1-9
Exercise 57 #1-14, 17

* * * For extra help, visit this link: http://www.freemathhelp.com/direct-variation.html * * *

Go For Gold
The last part of the class was taken up by receiving our Go For Gold booklets. It consists of 25 pages, and has multiple choice, short answer and long answer questions. Basically, we were told:
- it's worth 10% of our mark, and it's either 0% or 100%.
- even though you can ask for help, Ms. Armstrong will check your booklet ONCE, and only once. - you can ask others for help, compare and work together in a study group.
- you must show your work for EVERY question.
- last, but definitely not least, DUE DATE: Monday, January 22nd

The next blogger is Christine.