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Math Help - Slope of line , Equation Problem

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    Senior Member vaironxxrd's Avatar
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    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!!.
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    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
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    Senior Member vaironxxrd's Avatar
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    Quote Originally Posted by dwsmith View Post
    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
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    What don't you understand in particular?
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    Senior Member vaironxxrd's Avatar
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    Quote Originally Posted by dwsmith View Post
    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
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    Senior Member vaironxxrd's Avatar
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    Quote Originally Posted by dwsmith View Post
    What don't you understand in particular?
    Sorry i meant 18/3=6
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    \displaystyle 18=9*2=2*3*3

    \displaystyle \frac{2*3*3}{3}=\frac{3}{3}*2*3=6
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    Quote Originally Posted by vaironxxrd View Post
    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!)
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    Senior Member vaironxxrd's Avatar
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    Quote Originally Posted by SammyS View Post
    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
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    What are you trying to do? That is, what is the problem you are trying to solve?
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    Senior Member vaironxxrd's Avatar
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    Quote Originally Posted by HallsofIvy View Post
    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]
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  12. #12
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    Quote Originally Posted by vaironxxrd View Post
    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
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    Senior Member vaironxxrd's Avatar
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    Quote Originally Posted by skeeter View Post
    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
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    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
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    Senior Member vaironxxrd's Avatar
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    Quote Originally Posted by rtblue View Post
    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
    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!
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