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Homework Help: Graph problem

  1. Jul 23, 2009 #1
    hey guys, stuck on a few question, but dnt tell me the answer, direct me please :)

    how do i find the intercepts for;

    1. y = 1 / x -1
    2. y = 2 / x + 1
    3. y = 3 / 2x + 3

    cheers guys :):)
  2. jcsd
  3. Jul 23, 2009 #2


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    Staff: Mentor

    You mean the y intercept or the x intercept, or both? What does it mean for a graph to intercept an axis? What is the value of x at the y intercept(s)? What is the value of y at the x intercept(s)?
  4. Jul 23, 2009 #3
    how do i find x and y intercepts
  5. Jul 23, 2009 #4
    I think he means intersections of the curves

    Equate equation (1) and (2)
    Then (1) and (3)
    Then (2) and (3)

    Solve each equation individually to find all the x's and then plug them in to find the y's.

    Multiply by the LCD(least common denominator).
    You will probably end up with some quadratic equation.
  6. Jul 23, 2009 #5
    thanks, but how do i solve them, so ur saying 4 example;

    y = 3 / 2x + 3 -> y = 3(2x + 3) is that what u mean ?
  7. Jul 23, 2009 #6


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    Science Advisor
    Homework Helper

    Hi JakePearson! :smile:
    You mean the intercepts with the x and y axes?

    Those axes are y = 0 and x = 0 … soooo … you put y = 0 and solve for x, and x = 0 and solve for y. :smile:

    (oh, and the answer might be ∞)
  8. Jul 23, 2009 #7
    This isn't correct.

    Also, to JakePearson, please use parentheses. Otherwise, we are guessing as to what equations you posted. Do you mean

    1. y = (1/x) -1
    2. y = (2/x) + 1
    3. y = (3/(2x)) + 3


    1. y = 1/(x-1)
    2. y = 2/(x+1)
    3. y = 3/(2x+3)

    To elaborate on tiny-tim's good advice: to find the y-intercepts (the points where the curve intersects the y-axis, which is x=0), you set x=0 and then solve for y. Then those y values give you the y-intercepts, but list them as ordered pairs, i.e. (0,y) for each y value you find.

    To find the x-intercepts, it's a similar process: set y=0 (which is the x-axis) and then solve for x. Now all your x-intercepts are listed as (x,0).
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