Point Slope Form of an Equation

zee-f · 2011-05-27 06:27:29

32\-4= -8

bobbym · 2011-05-27 06:28:43

Correct, that is the slope! Now you just need to find b ( the y intercept ) in the slope form of an equation. How did they teach you to do that?

zee-f · 2011-05-27 07:01:41

y=mx+b

zee-f · 2011-05-27 08:30:27

115=8(1)+b
115=8+b
b=123
y=-8X+123

bobbym · 2011-05-27 09:11:28

That is the correct formula.

Now to do 14). They want Sams bill for July. July is the 7th month of the year. So just plug in:

That is his projected bill for July if that trend continues.

zee-f · 2011-05-27 21:32:35

in 13 its asking for the point slope so really 115=8(1)+b
115=8+b
b=123
y=-8X+123
is solving for 12 am spouse to do 13 in this equation y-k=m(x-h)
y-115=-8(x-1)
y-115=-8x--8
y-115=-8x+8
-115 -115

y=-8x+-107

is that correct?

Bob · 2011-05-27 23:10:12

hi zee-f

The point slope form just means showing the same equation in a different way:

point slope form

slope intersect form

You have this form in post #31

and you started correctly in your last post.

You had the right answer at line

y-115=-8(x-1)

Nothing more is needed for question (13).

But you went on and made a sign mistake. You must have because you would otherwise have got back to

Bob

Last edited by Bob (2011-05-27 23:14:23)

zee-f · 2011-05-27 23:37:44

ok thanx alot

zee-f · 2011-05-28 00:38:12

for number 15 are the ordered pairs (2001,20) (2008,4.5)

Bob · 2011-05-28 03:28:11

Yes, that'll do nicely.

Bob

zee-f · 2011-05-28 07:33:26

for number 16 this is what i got i was wondering if it was correct
y=mx+b

so the 4.5= 9/2
9/2-20/2008-2001= -31\2 over 7 =-31\14 so thats my slope
2001=(-31\14(20)+b
2001= -310\7+B
14317\7=b
y=-310/7X+14317/7

bobbym · 2011-05-28 08:18:38

Hi;

If you have written there:

That is not the equation that passes through those 2 points.

Please try again.

zee-f · 2011-05-28 08:36:37

did i start correct?like the beginning

bobbym · 2011-05-28 08:42:24

There are many errors:

First you changed from b to B, this is confusing in math. The variable is called little b. The 2001 is x not y. So in the earlier step you do not multiply by 20. The LHS should be 20 not 2001.

zee-f · 2011-05-28 21:41:20

16-m=(y2-y1)\(x2\x1)
(4.5-20)\(2008-2001)=
(9/2-40/2)\7=
(-31\2)\7= -31\14
Slope intercept
Y=(-31/14)x+b
20=(-31\14)(2,001)+b
B=20+62031/14=280\14+
62,031/14=62,311/14
Y=(-31/14)x+62311/14

zee-f · 2011-05-28 22:03:49

and for the point slope form this is whaT i got
y-k=m(x-h)
y-20=-31/14(x-2001)
y-20=-31/14x-62031\14

Bob · 2011-05-28 23:21:40

hi zee-f

slope intercept is correct

point slope is also good.

Well done!

No need for the face.

But very horrible numbers. You'd hope to get 'nice' values in the end ... after all someone just made these figures up, didn't they?

Bob

Last edited by Bob (2011-05-28 23:23:43)

zee-f · 2011-05-29 00:16:01

hhhh i didnt mean do do the sad face there spouse to be parentheses and yeah horrible numbers

zee-f · 2011-05-29 00:43:04

18. During which year was there 10 computers per student?
18- y= (-31/14)x+62311/14
Y = (-31/14)10+62311/14
Y=-155\7+62311\14
Y=-310\14+62311\14
Y=62001\14

bobbym · 2011-05-29 00:48:20

Hi;

Before you jump ahead, don't you think you want to check this answer.

zee-f wrote:

y-20=-31/14x-62031\14

Have you tried plugging x = 2001 into that?

zee-f · 2011-05-29 01:02:57

y-20=-31/14x-62031\14
y-20=-31/14*2011-62031/14
y-20=-62031\14-62031/14
y-20=0
-20 -20
Y=-20

bobbym · 2011-05-29 01:07:18

For x = 2001 , y = 20 not -20.

zee-f wrote:

y-20=-31/14x-62031\14

This equation does not pass through the point ( 2001, 20 )

zee-f · 2011-05-29 01:08:07

17- y-k=m(x-h)
y-20=-31\14X- -62031\14
-20 -20
Y=-31/14x- -62311/14

bobbym · 2011-05-29 01:11:20

Y=-31/14x- -62311/14

What does your use of - - mean? Is that a typo or are you meaning + ?

Your next line

-20 -20

Are you trying to cancel the -20?

zee-f · 2011-05-29 01:24:45

nop am subtracting 20 from both sides its asking for the point slope y-k=m(x-H)

Math Is Fun Forum

#26 2011-05-27 06:27:29

Re: Point Slope Form of an Equation

#27 2011-05-27 06:28:43

Re: Point Slope Form of an Equation

#28 2011-05-27 07:01:41

Re: Point Slope Form of an Equation

#29 2011-05-27 08:30:27

Re: Point Slope Form of an Equation

#30 2011-05-27 09:11:28

Re: Point Slope Form of an Equation

#31 2011-05-27 21:32:35

Re: Point Slope Form of an Equation

#32 2011-05-27 23:10:12

Re: Point Slope Form of an Equation

#33 2011-05-27 23:37:44

Re: Point Slope Form of an Equation

#34 2011-05-28 00:38:12

Re: Point Slope Form of an Equation

#35 2011-05-28 03:28:11

Re: Point Slope Form of an Equation

#36 2011-05-28 07:33:26

Re: Point Slope Form of an Equation

#37 2011-05-28 08:18:38

Re: Point Slope Form of an Equation

#38 2011-05-28 08:36:37

Re: Point Slope Form of an Equation

#39 2011-05-28 08:42:24

Re: Point Slope Form of an Equation

#40 2011-05-28 21:41:20

Re: Point Slope Form of an Equation

#41 2011-05-28 22:03:49

Re: Point Slope Form of an Equation

#42 2011-05-28 23:21:40

Re: Point Slope Form of an Equation

#43 2011-05-29 00:16:01

Re: Point Slope Form of an Equation

#44 2011-05-29 00:43:04

Re: Point Slope Form of an Equation

#45 2011-05-29 00:48:20

Re: Point Slope Form of an Equation

#46 2011-05-29 01:02:57

Re: Point Slope Form of an Equation

#47 2011-05-29 01:07:18

Re: Point Slope Form of an Equation

#48 2011-05-29 01:08:07

Re: Point Slope Form of an Equation

#49 2011-05-29 01:11:20

Re: Point Slope Form of an Equation

#50 2011-05-29 01:24:45

Re: Point Slope Form of an Equation

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