Friday, July 23rd, 2010

### Solution:

- 2x – =y=61
- 2x + y= =7

If you subtract the second equation from the first, you can eliminate x and you are left with -4y = 68.

So y = 3D -17, and plugging this into the first equation we can figure out

y: 2x = (-51)=61,

so **x = 5**

Friday, July 23rd, 2010

### Solution:

The expression “9/10 of 80” can be written as

This is equal to 72.

Friday, July 23rd, 2010

### Solution:

A six-sided polygon is known as a Hexagon:

Friday, July 23rd, 2010

### Solution:

In the physical sciences, the amount of a sample is often given in terms of moles (i.e. Avogadro’s number, or 6.02214179 x 10^{23}):

Friday, July 23rd, 2010

### Solution:

First write down the two equations and then pick several values of x and use those values to calculate the corresponding values of y. You can use the x,y pairs to then plot each line. You will see that the two lines intersect at 2,8 =i.e. x=2 and y=8).

Friday, July 23rd, 2010

### Solution:

First, let’s plot f(x) =

Here’s what the graph looks like:

Now, the definition of “domain of a function” as follows: The domain of a given function is the set of “input” values for which the function is defined.” For instance, the domain of cosine would be all real numbers, while the domain of the square root would be only numbers greater than or equal to 0 (ignoring complex numbers in both bases).

As you can see from the above graph, the function is valid for all “real” values of x, except for 0. The set of “real numbers”, as you may know, can be thought of as points on an infinitely long number line. The shorthand way of saying “all real numbers except for x” is as follows: