Follow-up on my last post

bobbym · 2012-06-27 04:22:02

That is what I am showing you how to do step by step. We are only on the first step. If you place the correct x1 into the formula we will be almost done.

Since x1 = 1 we put it into the formula where the x1 is.

SlowlyFading · 2012-06-27 04:39:46

(x1, x2,) = (1, 115)
(y1, y2) = (5, 83)

How's that?

bobbym · 2012-06-27 05:17:11

Hi;

(x1,y1) = (1,115)
(x2,y2) = (5,83)

SlowlyFading · 2012-06-27 05:20:53

I thought we had to break 1,115 into two points? And the same with 5,83

bobbym · 2012-06-27 07:03:52

No, we need the x coordinate and the y coordinate.

This is how a point is written (x coordinate, y coordinate).

SlowlyFading · 2012-06-27 07:06:16

But then that's only (x1, x2) not (x1, x2) and (y1, y2)?

bobbym · 2012-06-27 07:07:45

Hold on that is not x1 and x2. Each point has an x and a y. They are written (x1,y1) not (x1,x2).

SlowlyFading · 2012-06-27 07:13:08

Okay, so then it's:

(x1, y1) = (1, 115)
(x2, y2) = (5, 83)

bobbym · 2012-06-27 07:14:44

Correct! We use the first one and here is where they go.

Now what do you have for the slope?

SlowlyFading · 2012-06-27 07:20:29

-32/4

bobbym · 2012-06-27 07:23:00

Can you reduce that?

SlowlyFading · 2012-06-27 07:25:05

It reduces down to -0.125 I believe.

bobbym · 2012-06-27 07:26:38

That would be correct for -4 / 32. Your answer is -32 / 4.

SlowlyFading · 2012-06-27 07:28:34

-8?

bobbym · 2012-06-27 07:29:53

Correct!

Okay, where does the - 8 go?

SlowlyFading · 2012-06-27 07:36:10

y -k = 8(x - h)

SlowlyFading · 2012-06-27 07:37:15

y -k = -8(x - h)

bobbym · 2012-06-27 07:38:33

Hi;

I meant in this equation.

SlowlyFading · 2012-06-27 07:43:24

(y - 115) = 8 (x - 1)

bobbym · 2012-06-27 07:44:24

Close but not quite. What happened to the minus sign in front of the 8?

SlowlyFading · 2012-06-27 07:47:47

It was an accident, it's supposed to be there. (y - 115) = -8 (x - 1)

bobbym · 2012-06-27 07:49:59

Yep, you are done! That is the point slope form.

SlowlyFading · 2012-06-27 07:57:37

Cool, thank you! One last question, "If this trend continues, what will Sam's bill be in July?"

So, I need to change

(x1, y1) = (1, 115)
(x2, y2) = (5, 83)

to

(x1, y1) = (1, 115)
(x2, y2) = (7, 83)

And then do the same thing?

bobbym · 2012-06-27 08:05:25

Hi SlowlyFading;

You just plug in the the x = 7 in the equation you found.

Add 115 to both sides.

SlowlyFading · 2012-06-27 08:12:59

Okay BobbyM, thanks a lot for all the help!
I'm sure I got annoying at times and as you can see math isn't my strong-point, nonetheless thanks!

Math Is Fun Forum

#51 2012-06-27 04:22:02

Re: Follow-up on my last post

#52 2012-06-27 04:39:46

Re: Follow-up on my last post

#53 2012-06-27 05:17:11

Re: Follow-up on my last post

#54 2012-06-27 05:20:53

Re: Follow-up on my last post

#55 2012-06-27 07:03:52

Re: Follow-up on my last post

#56 2012-06-27 07:06:16

Re: Follow-up on my last post

#57 2012-06-27 07:07:45

Re: Follow-up on my last post

#58 2012-06-27 07:13:08

Re: Follow-up on my last post

#59 2012-06-27 07:14:44

Re: Follow-up on my last post

#60 2012-06-27 07:20:29

Re: Follow-up on my last post

#61 2012-06-27 07:23:00

Re: Follow-up on my last post

#62 2012-06-27 07:25:05

Re: Follow-up on my last post

#63 2012-06-27 07:26:38

Re: Follow-up on my last post

#64 2012-06-27 07:28:34

Re: Follow-up on my last post

#65 2012-06-27 07:29:53

Re: Follow-up on my last post

#66 2012-06-27 07:36:10

Re: Follow-up on my last post

#67 2012-06-27 07:37:15

Re: Follow-up on my last post

#68 2012-06-27 07:38:33

Re: Follow-up on my last post

#69 2012-06-27 07:43:24

Re: Follow-up on my last post

#70 2012-06-27 07:44:24

Re: Follow-up on my last post

#71 2012-06-27 07:47:47

Re: Follow-up on my last post

#72 2012-06-27 07:49:59

Re: Follow-up on my last post

#73 2012-06-27 07:57:37

Re: Follow-up on my last post

#74 2012-06-27 08:05:25

Re: Follow-up on my last post

#75 2012-06-27 08:12:59

Re: Follow-up on my last post

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