writing an equation given 2 points

[Rosey]

Latonya buys CDs for a fee per CD plus a fixed amount for postage and handling: that is the amount for Postage and Handling are the same no matter how many archive CDs she purchases. Last month, Latonya paid $7.00 for two archive CDs and this month she paid $13.00 for five archive CDs.

Write 2 ordered pairs such that the x coordinate is the number of archive CDs purchased and the y coordinate is the total cost of archiving the photos.
I think I get this: (2,7), (5,13)

Write an equation for the total cost, y , for x archive CDs.
Do I use the equation m= y2 - y1/x2-x1?
where m= 2? is that right? The CDs cost $2.00 to mail?

What is the domain of the equation found in b? Write answer in set builder notation. I don't understand this one or the next one!! Please help!

What is te range of the quotation found in b? Write answer in set builder notation.

 

[stapel]

Latonya buys CDs for a fee per CD plus a fixed amount for postage and handling: that is the amount for Postage and Handling are the same no matter how many archive CDs she purchases. Last month, Latonya paid $7.00 for two archive CDs and this month she paid $13.00 for five archive CDs.

Write 2 ordered pairs such that the x coordinate is the number of archive CDs purchased and the y coordinate is the total cost of archiving the photos.
I think I get this: (2,7), (5,13)

Looks good to me! :wink:

Write an equation for the total cost, y , for x archive CDs.
Do I use the equation m= y2 - y1/x2-x1?
where m= 2? is that right? The CDs cost $2.00 to mail?

You have the right slope. Now you need to find the line equation. Pick one of the points (it doesn't matter which), and plug it and the slope into the point-slope form of a straight line. Solve this equation for "y=" to get the equation they're wanting.

What is the domain of the equation found in b? Write answer in set builder notation. I don't understand this one or the next one!! Please help!

The domain is the set of all allowable inputs. So think about the set. Can you have a set that looks like {x | x = -2, -1, 0, 3}? Of course not! She can't buy negative numbers of CDs! Can you have a domain that looks like {x | x = 0, 1, 3.5, 7.2}? Of course not! She can't buy fractions of discs!

So what would the domain look like?

What is te range of the quotation found in b? Write answer in set builder notation.

Plug your inputs into the formula you created, and note the pattern in the outputs. Or, better yet, find the pattern for the inputs (namely, "whole numbers" or "the naturals"), and use the formula you created as the "rule": {y | y = (your equation), for x = (what you got for the domain)}.

 

[swatiSF]

Latonya buys CDs for a fee per CD plus a fixed amount for postage and handling: that is the amount for Postage and Handling are the same no matter how many archive CDs she purchases. Last month, Latonya paid $7.00 for two archive CDs and this month she paid $13.00 for five archive CDs.

Write 2 ordered pairs such that the x coordinate is the number of archive CDs purchased and the y coordinate is the total cost of archiving the photos.
I think I get this: (2,7), (5,13)

Write an equation for the total cost, y , for x archive CDs.
Do I use the equation m= y2 - y1/x2-x1?
where m= 2? is that right? The CDs cost $2.00 to mail?

What is the domain of the equation found in b? Write answer in set builder notation. I don't understand this one or the next one!! Please help!

What is te range of the quotation found in b? Write answer in set builder notation.

Y = mX + b

M = Slope = (13-7)/(5-2) = 6/3 = 2

Pick a point and plug it in, solve for b

7 = (2)(2) + B
B = 3

...

I hope this helps!!