# Thread: Slope of line , Equation Problem

1. ## Slope of line , Equation Problem

I got Point P(9,-1) , M(slope)=Fraction 2/3
when i get to do -1=(fraction)2/3(9) I don't know what to do help!!.

2. The slope of the tangent line: $\displaystyle y-y_1=m(x-x_1)\rightarrow y-(-1)=\frac{2}{3}(x-9)\rightarrow y=\frac{2x}{3}-6-1=\frac{2x}{3}-7$

$\displaystyle \frac{2*9}{3}=\frac{2*3*3}{3}=2*3=6$

3. Originally Posted by dwsmith
The slope of the tangent line: $\displaystyle y-y_1=m(x-x_1)\rightarrow y-(-1)=\frac{2}{3}(x-9)\rightarrow y=\frac{2x}{3}-6-1=\frac{2x}{3}-7$

$\displaystyle \frac{2*9}{3}=\frac{2*3*3}{3}=2*3=6$
I really din't uunderstand much about it

4. What don't you understand in particular?

5. Originally Posted by dwsmith
What don't you understand in particular?
The 2*9/2 , 2*3*3/2
I know 2*9-18/2=9 but 2*3=6*3=18/2=9 oh i got it, haha now i understand

6. Originally Posted by dwsmith
What don't you understand in particular?
Sorry i meant 18/3=6

7. $\displaystyle 18=9*2=2*3*3$

$\displaystyle \frac{2*3*3}{3}=\frac{3}{3}*2*3=6$

8. Originally Posted by vaironxxrd
I got Point P(9,-1) , M(slope)=Fraction 2/3
when i get to do -1=(fraction)2/3(9) I don't know what to do help!!.
The slope-intercept form for a line is:

$y=mx+b, \text{ where } m$ is the slope and $b$ is the y-intercept.

You have a point, P, with x & y values and you also have the slope. Plug these in to find what b is.

$-1=\frac23(9)+b$. (You were very close to this.) Now solve for b and put that back into:

$y=\frac23(x)+b$. (b is the number you just found, of course!)

9. Originally Posted by SammyS
The slope-intercept form for a line is:

$y=mx+b, \text{ where } m$ is the slope and $b$ is the y-intercept.

You have a point, P, with x & y values and you also have the slope. Plug these in to find what b is.

$-1=\frac23(9)+b$. (You were very close to this.) Now solve for b and put that back into:

$y=\frac23(x)+b$. (b is the number you just found, of course!)
yea i know but when i multiply the fraction i don't know what to do after that

10. What are you trying to do? That is, what is the problem you are trying to solve?

11. Originally Posted by HallsofIvy
What are you trying to do? That is, what is the problem you are trying to solve?
Once i have the slope which is (Fraction) 2/3 I have to do (X) which is 9 so i guess that is gonna give me 2/3 again when i simplify the fraction i got. Look at the picture for better explanation. and for reference scroll up and look at the problem, because i am a really bad explainer.
[IMG][/IMG]

12. Originally Posted by vaironxxrd
Once i have the slope which is (Fraction) 2/3 I have to do (X) which is 9 so i guess that is gonna give me 2/3 again when i simplify the fraction i got. Look at the picture for better explanation. and for reference scroll up and look at the problem, because i am a really bad explainer.
[IMG][/IMG]
I have no idea what you are doing or why you are doing it.

as SammyS stated ...

$y = mx + b$

substitute in the given x and y values , and the given slope, then solve for b.

$-1 = \frac{2}{3}(9) + b$

$-1 = 6 + b$

subtract 6 from both sides of the equation ...

$b = -7$

so ... the linear equation that passes throught the point $(9,-1)$ with slope $m = \frac{2}{3}$ is $y = \frac{2}{3} x - 7$

13. Originally Posted by skeeter
I have no idea what you are doing or why you are doing it.

as SammyS stated ...

$y = mx + b$

substitute in the given x and y values , and the given slope, then solve for b.

$-1 = \frac{2}{3}(9) + b$

$-1 = 6 + b$

subtract 6 from both sides of the equation ...

$b = -7$

so ... the linear equation that passes throught the point $(9,-1)$ with slope $m = \frac{2}{3}$ is $y = \frac{2}{3} x - 7$
i understand almost the whole equation except How do you get the 6?, Because 2*9=18 and 3*9=27

14. Your work is flawed vaironxxrd.

In the image you gave, this is your work:

$\frac{2}{3}*9=\frac{18}{27}\div\frac{3}{3}=\frac{2 }{3}$

This is incorrect. Actually, we have:

$\frac{2}{3}*\frac{9}{1}=\frac{18}{3}=6$

note that $\frac{9}{1}=9$

As the others have been saying now we use the slope intercept form: $y=mx+b$

Where x and y are the x and y coordinates of a point, m is the slope, and b is the y-intercept.

You have one point: (9,-1) and the slope as 2/3, so we will use this:

$-1=\frac{2}{3}*9+b$ This step is where your error was.

$-1=6+b$

$b=-7$

Now we put this into y-intercept form:

$y=\frac{2}{3}x-7$

15. Originally Posted by rtblue

In the image you gave, this is your work:

$\frac{2}{3}*9=\frac{18}{27}\div\frac{3}{3}=\frac{2 }{3}$

This is incorrect. Actually, we have:

$\frac{2}{3}*\frac{9}{1}=\frac{18}{3}=6$

note that $\frac{9}{1}=9$

As the others have been saying now we use the slope intercept form: $y=mx+b$

Where x and y are the x and y coordinates of a point, m is the slope, and b is the y-intercept.

You have one point: (9,-1) and the slope as 2/3, so we will use this:

$-1=\frac{2}{3}*9+b$ This step is where your error was.

$-1=6+b$

$b=-7$

Now we put this into y-intercept form:

$y=\frac{2}{3}x-7$
Thanks that was a good mind refresher, I really am forgetting everything about 1 week later which is of course bad.but yea in other to multiply a fraction we need another fraction and then the other stuff i understand it . Thanks very much!