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Need Help With Learning Slope Intercept Form(Not Homework)

  1. Oct 22, 2013 #1
    So being as much of a simpleton as me I don't understand slope intercept form. I can graph simple linear equations like x=y+3 and things like that but I want to learn about slope intercept form and what it is(I have been entreating people like my friends, math teacher and parents to help me so this wasn't my first choice). Can anybody can please help me understand harder equations? As proof that I am not doing this to get the answer to a homework problem YOU get to design an equation for me. Now remember you are dealing with an idiot with -∞ I.Q so don't expect much.
  2. jcsd
  3. Oct 22, 2013 #2


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    Slope intercept form just uses the following fact: If you have a line, then if you pick any two points [itex] (x_1, y_1)[/itex] and [itex] (x_2,y_2) [/itex] you get that
    [tex] \frac{ y_2-y_1}{x_2-x_1} = m [/tex]
    where m is the slope of the line. In particular if I tell you the slope of the line and a point on it, let's say the slope is 3 and (1,5) is a point on the line, then if (x,y) is on the line it must satisfy
    [tex] \frac{y-5}{x-1} = 3 [/tex]
    where 3 is the m above, (1,5) is the [itex] (x_1,y_1)[/itex] above and (x,y) is the [itex] (x_2,y_2)[/itex] above. This equation is the point slope form of the line.
  4. Oct 22, 2013 #3


    Staff: Mentor

    What Office_Shredder described is actually the point-slope form of the equation of a line. In his example the equation uses a point on the line (1, 5) and the slope (3).

    The slope-intercept form uses the slope and y-intercept.

    From (y - 5)/(x - 1) = 3, multiply both sides by x - 1 to get y - 5 = 3(x - 1) = 3x - 3. Add 5 to both sides to get y = 3x - 3 + 5, or
    y = 3x + 2

    Here the slope is 3 (as before) and the y-intercept is 2, which means that the line goes through (0, 2).
  5. Oct 22, 2013 #4
    I get it now thanks. Just recently I found a good youtube video that I couldn't finish watching but showed me a lot that helped me understand. Now that I have a rolling start I can probably be able to solve and learn more about slope intercept form without difficulty. When I was first learning people would give me advanced equations without even defining what slope intercept form is. Thaank you for your help.
  6. Oct 22, 2013 #5


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    OK, I obviously need to get more sleep :redface:
  7. Oct 23, 2013 #6
    Very happy the you mentioned this Office_Shredder because now I know what I should learn next. To the land of youtube that throws up a counterfeit of entertainment but can be used for good things to.
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