Math homework *crappy photo included*

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[ARCHIVED THREAD] - Math homework *crappy photo included*

Posted: 12/11/2013 12:39:49 PM EDT

I had a horrible time getting a scanned photo of the page.

My son is suppose to Identify the slope and y-intercept of each graph, then write a corresponding linear equation in slope-intercept form. I was able to figure out 1-3 but then got over my head with the rest. If someone can tell me how to do this, how to understand it, I would be very grateful.

Posted: 12/11/2013 12:43:37 PM EDT

[#1]

The answer is 87.

Posted: 12/11/2013 12:44:59 PM EDT

[#2]

Y = mx + b

Posted: 12/11/2013 12:45:19 PM EDT

[#3]

Rise over Run

Posted: 12/11/2013 12:45:25 PM EDT

[#4]

Odd-numbered answers are in the back

Posted: 12/11/2013 12:45:51 PM EDT

[#5]

I think #4 is y=2

Posted: 12/11/2013 12:47:26 PM EDT

[#6]

Do you know about Khan Academy?

Posted: 12/11/2013 12:47:28 PM EDT

[#7]

Four and six are kinda trick questions, but what was the problem solving 5?

ETA What did you get trying to solve 5?

Posted: 12/11/2013 12:48:40 PM EDT

[#8]

Don't they explain it at the begining of the lesson?

Or google how to do it.

Posted: 12/11/2013 12:49:50 PM EDT

[#9]

Slope intercept form is y=mx +b. Y is the height on your graph. M is the slope. X is your independent variable. And b is the height of the line where it crosses the y axis.

To find the slope find the ratio of the amount the line rises divided by the amount it "runs" or moves horizontally. In the case of a purely horizontal line the equation is y=height of line

Posted: 12/11/2013 12:51:36 PM EDT

[#10]

Quote History

Quoted:

Four and six are kinda trick questions, but what was the problem solving 5?

ETA What did you get trying to solve 5?

View Quote

I got b=0, m = -3+5 but the back of the book states: m= -2/3 b=0 & y = -2/3 so I obviously do not know what I'm doing!

Posted: 12/11/2013 12:51:58 PM EDT

[#11]

Graphs Using Slope-Intercept Form

Posted: 12/11/2013 12:52:27 PM EDT

[#12]

Quote History

Quoted:

Slope intercept form is y=mx +b. Y is the height on your graph. M is the slope. X is your independent variable. And b is the height of the line where it crosses the y axis.

To find the slope find the ratio of the amount the line rises divided by the amount it "runs" or moves horizontally. In the case of a purely horizontal line the equation is y=height of line

View Quote

okay now this makes sense. Let me try. Thank you.

Posted: 12/11/2013 12:54:17 PM EDT

[#13]

What is his level of participation in solving these problems? Sounds like you are the one doing the homework assignment.

Posted: 12/11/2013 12:58:54 PM EDT

[#14]

Proper arfcom math protocol is to only misunderstand/hate DIFFERENT ways of teaching mathematics. There is no call for a thread like this.

Posted: 12/11/2013 12:59:05 PM EDT

[#15]

Quote History

Quoted:

What is his level of participation in solving these problems? Sounds like you are the one doing the homework assignment.

View Quote

so far none. He's sick and hasn't been to class so I'm trying to understand them before I teach it to him.

Posted: 12/11/2013 12:59:51 PM EDT

[#16]

Do you even lift bro?

Posted: 12/11/2013 1:00:11 PM EDT

[#17]

Quote History

Quoted:
I got b=0, m = -3+5 but the back of the book states: m= -2/3 b=0 & y = -2/3 so I obviously do not know what I'm doing!

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:

Four and six are kinda trick questions, but what was the problem solving 5?
ETA What did you get trying to solve 5?

I got b=0, m = -3+5 but the back of the book states: m= -2/3 b=0 & y = -2/3 so I obviously do not know what I'm doing!

-3+5=2. Lines with positive slope rise from left to right, so you can tell at a glance that this line has negative slope. Also, a slope of 1 is 45 deg. (it rises 1 unit for every 1 unit it runs), so you can tell at a glance that the slope is larger than -1 (IOW, it's between 0 and -1).

ETA: I tried to rewrite the last part to make it less confusing, but I'm not sure that I succeeded. What I mean is that a line with a positive slope of greater than one will be steeper than 45 deg. and rise from left to right. A line with a slope of less than -1 (think of numbers on the number line, -2 is less than -1) will fall from left to right, and be steeper than 45 deg.

Posted: 12/11/2013 1:01:35 PM EDT

[#18]

Quote History

Quoted:
Graphs Using Slope-Intercept Form

http://www.youtube.com/watch?v=9wOalujeZf4

View Quote

That video is doing a much better job explaining it than I would.

Posted: 12/11/2013 1:06:30 PM EDT

[#19]

4)

Y Intercept.... 2

Equation y = 0x + 2
y = 2

5)

Y Intercept........ 0

Equation y = -(2/3)x +0
y = -(2/3)x

6)

Y Intercept.......NONE

Equation x = 2

Whenever these is a horizontal, or a vertical line it means that either X or Y is the same for all values of Y or X.

So for number 6, X will always be 2 no matter what value of Y. How can this be? Y in the equation is multiplies by 0 so whatever number you put in the equation, the Y value will never effect the outcome.

Posted: 12/11/2013 1:09:42 PM EDT

[#20]

Whythefox you did well. Thank you.

Posted: 12/11/2013 1:12:11 PM EDT

[#21]

Quote History

Quoted:
Odd-numbered answers are in the back

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Genius

Posted: 12/11/2013 1:14:45 PM EDT

[#22]

m is the slope.
b is the y intercept.
Slope intercept form is y=mx+b.

Problem 4
Lets find the Y intercept (outside of just looking at it).

We need to find the equation as it passes through the points, 2,2 (x1,y1) and -2,2 (x2,y2)

We know Y = 2 at a value of X = 0.

Slope formula is

m = (y1) - (y2) / (x1) - (x2)
m = (2 - 2) / (2 - -2)
m = 0 / 4
m = 0

Now we know the slope is 0.
Find y intercept (b) where the slope is 0 (m, which we figured out above) and for point -2,2 (any point on line)
y=mx+b
2 = 0*-2 + b
2 = b
b = 2

Now solve the equation.
y = mx+b
y = 0x + 2
The equation in this case will simply be y = 2.

Thus:
Your y intercept is 2
Your slope is 0
Your equation is y = 2

Posted: 12/11/2013 1:16:02 PM EDT

[#23]

288

Posted: 12/11/2013 1:27:43 PM EDT

[#24]

Would you like me to walk through the rest of the problems in the same way I did above or have you received enough information?

Posted: 12/11/2013 1:38:44 PM EDT

[#25]

Take two points to find the slope.

Suppose the points are (x1,y1) and (x2,y2).

Then, the slope is m=(y2-y1)/(x2-x1).

The point intercept form of a linear curve is y=mx+b.

You know m.

Now pick a point, such as (x1,y1) and plug it in.

y1=mx1+b.

Solve for b.

b=y1-mx1.

Now you have m and b. Write out the linear curve.

y=mx+b.

Check your work by plugging in x2 and making sure that you get y2.

ETA: Let me know if this is not clear. If not, then I will type it up in LaTex so it looks nice and send it to you via IM.

Posted: 12/11/2013 1:50:11 PM EDT

[#26]

Quote History

Quoted:

Would you like me to walk through the rest of the problems in the same way I did above or have you received enough information?

View Quote

I've got it, thank you! I didn't understand the slope but I've got it. I haven't done this in 30 years though so more than likely I'll struggle tomorrow.

Posted: 12/11/2013 7:01:33 PM EDT

[#27]

To find the best fit line you need to use the "least squares method" and calculate the R^2 value.

Excel can do this for you.

Posted: 12/11/2013 7:04:22 PM EDT

[#28]

This doesn't help, but I thought it was cool

[ARCHIVED THREAD] - Math homework *crappy photo included*

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