help please am sooooooo confused :((

zee-f · 2011-05-16 06:06:59

16. The bigger the number the slope is in the equation, what do you notice happens to the graph?

17.What common characteristic do you notice about graphs with a positive slope? Is there a similar common characteristic for graphs with negative slopes?

18. What would the slope of the graph that goes through the two points (-3, 4) and (2, 4) be? What would this graph look like? Think back to lesson 10, What should the equation of this line be?

19.What would the y-intercept of the equation y = 3/4x be?

20. When we have zero on the bottom of the slope, we call that no slope because of the rule that zero can never be in the denominator of a fraction. An example of this would be a line that goes through the points (2, -3) and (2, 4). If you plotted these points, what would this graph look like? What should this equation be?

Bob · 2011-05-16 06:46:46

hi zee-f

These questions are steering you towards what mathematicians call 'the equation of a straight line graph".

'm' is a number for the size of the slope ( or gradient) of the line and 'c' the point where the line crosses the y axis. (the intercept)

Have a look at

http://www.mathsisfun.com/equation_of_line.html

for the general rules for straight line graphs

and to experiment with different values of m and c

http://www.mathsisfun.com/data/straight_line_graph.html

That should help you to explore these questions.

Looking at them, you may find you can do them in a different order from the order they are set. So don't give up if you cannot do one of them. Try the others and understanding may come.

Post again after you have tried both those links.

Bob

Last edited by Bob (2011-05-16 06:49:37)

zee-f · 2011-05-17 00:58:03

can anybody help me i did numbers 20 and 18 but i just cant figure the other ones out

16. The bigger the number the slope is in the equation, what do you notice happens to the graph?

17.What common characteristic do you notice about graphs with a positive slope? Is there a similar common characteristic for graphs with negative slopes?

18. What would the slope of the graph that goes through the two points (-3, 4) and (2, 4) be? What would this graph look like? Think back to lesson 10, What should the equation of this line be?
The slope for (-3, 4) and (2, 4) would be
M=(4-4)/(2-3)=0/5
M=0/5
Y=mx+b
2=0/5*4+b
2=0+b
B=2
Y=0/5x+2
It looks like a horizontal line so the equation should be y=2

19- What would the y-intercept of the equation y = 3/4x be?

20. When we have zero on the bottom of the slope, we call that no slope because of the rule that zero can never be in the denominator of a fraction. An example of this would be a line that goes through the points (2, -3) and (2, 4). If you plotted these points, what would this graph look like? What should this equation be?

#20-

(2, -3) and (2, 4).

m=4+3/2-2
m=7/0
slope is undefined
so the line would look like a vertical line

bobbym · 2011-05-17 01:23:59

Hi;

16)

http://www.mathsisfun.com/graph/functio … =-8&ymax=8

The blue line ( y = 1*x ) has a slope of 1 while the red line ( y = 2*x ) has a slope of 2. What do you notice? Try a few more.

19) The y intercept is 0.

Remember the general form of a linear equation.

y = mx + b. m is the slope and b is the y intercept.

Bob · 2011-05-17 03:27:03

hi zee-f

16. The bigger the number the slope is in the equation, what do you notice happens to the graph?

I think all this is asking for is that as 'm' gets bigger the line gets steeper. You probably were looking for something more difficult.

17.What common characteristic do you notice about graphs with a positive slope? Is there a similar common characteristic for graphs with negative slopes?

If you have experimented with

http://www.mathsisfun.com/data/straight_line_graph.html

you should have noticed that when m is positive the line slopes up to the right
and when m is minus the line slopes down.

18. What would the slope of the graph that goes through the two points (-3, 4) and (2, 4) be? What would this graph look like? Think back to lesson 10, What should the equation of this line be?
The slope for (-3, 4) and (2, 4) would be
M4-4)/(2-3)=0/5
M=0/5
Y=mx+b
2=0/5*4+b
2=0+b
B=2
Y=0/5x+2
It looks like a horizontal line so the equation should be y=2

THIS IS (LATER EDIT) NOT QUITE CORRECT! SEE post # 9. My thanks to glenn101 for spotting this!

19- What would the y-intercept of the equation y = 3/4x be?

The 'c' term is missing entirely or think of this as y = 3x/4 + 0.
So the intercept is 0.

Another way to get any intercept with the y axis is to set x = 0 in the equation y = mx + c.

In this case y = 3/4 of 0 = 0. So the line goes through the point (0,0)

20. When we have zero on the bottom of the slope, we call that no slope because of the rule that zero can never be in the denominator of a fraction. An example of this would be a line that goes through the points (2, -3) and (2, 4). If you plotted these points, what would this graph look like? What should this equation be?

#20-

(2, -3) and (2, 4).

m=4+3/2-2
m=7/0
slope is undefined
so the line would look like a vertical line

YES IT WOULD. Well done. But which line? Notice that x = 2 for both points.
If the line goes straight up the x coordinate must always be 2 so the equation for this special case is x = 2

Bob

ps. to bobbym. How are you now? flu over I hope?

Last edited by Bob (2011-05-17 21:19:35)

zee-f · 2011-05-17 07:56:58

thanx alot )

bobbym · 2011-05-17 18:04:25

Hi Bob;

ps. to bobbym. How are you now? flu over I hope?

Not fully gone yet, thanks for asking.

glenn101 · 2011-05-17 20:57:39

Sorry to interrupt but wouldn't the graph be y=4?
it passes through (-3,4) and (2,4) if this means (x,y).
As the y coordinate is repeated for 2 different x-values and we know it is a line why is it y=2?

Last edited by glenn101 (2011-05-17 20:59:37)

Bob · 2011-05-17 21:17:42

Thanks glenn101,

Sorry to interrupt

You don't have to apologise for posting some wisdom after my posts. Just be gentle with me when you spot I've done something stupid.

Yes you are right. How did I come to miss that?

I'll go back to the working from post #3

18. What would the slope of the graph that goes through the two points (-3, 4) and (2, 4) be? What would this graph look like? Think back to lesson 10, What should the equation of this line be?

The slope for (-3, 4) and (2, 4) would be

M= (4-4)/(2- -3)=0/5

M=0/5 = 0

Y=mx+b

2=0/5*4+b

ARRH! HERE WE ARE. THE COORDINATES ARE BACK TO FRONT! IT SHOULD BE:

4 = (0/5)*2 + b

4=0+b

b=4

Y=0/5x+4

It looks like a horizontal line so the equation should be y=4

Hope you spot this correction zee-f

Bob

Last edited by Bob (2011-05-17 21:23:04)

glenn101 · 2011-05-17 22:08:55

No worries bob:) I was just getting concerned for a second there haha Glad to help

Last edited by glenn101 (2011-05-17 22:11:31)

jacoloco · 2011-05-17 23:44:39

help. the question is-a swimming pool is in the shape of a cuboid.
the length of the swimming pool is 50 m and its width is 25 m
the volume of water in the pool is 3,750,000 litres.

the floor of the pool is horizontal
1 m to the power of three = 1000 litres
work out the depth of the water in the pool. - please help.

Bob · 2011-05-17 23:56:00

hi jacoloco

Volume of the pool (as it is a cuboid) is V = L x W x H

In your question you know V = 3 750 000 Litres = 3750 cubic metres (important to have all the units the same!)

L = 50 m and W = 25 m. H is what you want to know.

So 3750 = 50 x 25 x H

50 x 25 = 1250

so 3750 = 1250 x H

Do 3750 / 1250 = H So just divide.

Post back an answer and I'll say if it is right.

Bob

Last edited by Bob (2011-05-18 00:00:38)

Math Is Fun Forum

#1 2011-05-16 06:06:59

help please am sooooooo confused :((

#2 2011-05-16 06:46:46

Re: help please am sooooooo confused :((

#3 2011-05-17 00:58:03

Re: help please am sooooooo confused :((

#4 2011-05-17 01:23:59

Re: help please am sooooooo confused :((

#5 2011-05-17 03:27:03

Re: help please am sooooooo confused :((

#6 2011-05-17 07:56:58

Re: help please am sooooooo confused :((

#7 2011-05-17 18:04:25

Re: help please am sooooooo confused :((

#8 2011-05-17 20:57:39

Re: help please am sooooooo confused :((

#9 2011-05-17 21:17:42

Re: help please am sooooooo confused :((

#10 2011-05-17 22:08:55

Re: help please am sooooooo confused :((

#11 2011-05-17 23:44:39

Re: help please am sooooooo confused :((

#12 2011-05-17 23:56:00

Re: help please am sooooooo confused :((

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