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anonymous

  • 5 years ago

Can someone explain finding the equation of a line step by step

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  1. anonymous
    • 5 years ago
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    There are a number of ways to do it depending on what information you have. Typically you'll be given either a point and a slope, or given 2 points.

  2. anonymous
    • 5 years ago
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    Okay say im given two points

  3. anonymous
    • 5 years ago
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    Ok, then you must first find the slope.

  4. anonymous
    • 5 years ago
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    Do you know how to find the slope of a line, given 2 points?

  5. anonymous
    • 5 years ago
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    No

  6. anonymous
    • 5 years ago
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    \[Slope =\frac{y_2-y_1}{x_2-x_1}\] Where \((x_1,y_1)\) is the first point and \((x_2,y_2)\) is the second.

  7. anonymous
    • 5 years ago
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    The slope is how much the function (y) changes as the input (x) changes.

  8. anonymous
    • 5 years ago
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    Our teacher said it's pretty much rise over run correct?

  9. anonymous
    • 5 years ago
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    So \[ Slope = \frac{\text{Change in y}}{\text{Change in x}}\] And we can find the difference in x and the difference in y by subtracting the x and y values at the respective points.

  10. anonymous
    • 5 years ago
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    Yes. How much you rise over how far you ran.

  11. anonymous
    • 5 years ago
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    Once you know the slope, you can plug in the slope, and one of your points into the point slope formula.

  12. anonymous
    • 5 years ago
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    So if I had a line that passes through (2,4) and (8, 7) wouldn't the slope be 3/6

  13. anonymous
    • 5 years ago
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    Yes, but you can simplify that.

  14. anonymous
    • 5 years ago
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    To 1/2?

  15. anonymous
    • 5 years ago
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    Yes

  16. anonymous
    • 5 years ago
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    Now plug that slope into the point slope formula along with one of your points.

  17. anonymous
    • 5 years ago
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    Okay so if I had (-4,8) and (3, 1) It would be 7/7?

  18. anonymous
    • 5 years ago
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    Not quite.

  19. anonymous
    • 5 years ago
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    Double check that you are putting the same point for x1 that you're putting for y1 and vice versa.

  20. anonymous
    • 5 years ago
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    It doesn't matter which one you pick to be point 1 or point 2, but you have to keep them consistant. You can't use one for point 1 on top, then switch it on the bottom.

  21. anonymous
    • 5 years ago
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    Okay, makes sense. So say they give me just y=-2x, what does that mean

  22. anonymous
    • 5 years ago
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    That means you have the slope intercept form.

  23. anonymous
    • 5 years ago
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    y=mx + b

  24. anonymous
    • 5 years ago
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    where the coefficient on the x term is your slope.

  25. anonymous
    • 5 years ago
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    m is your slope.

  26. anonymous
    • 5 years ago
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    So how do I put it into y=mx+b form?

  27. anonymous
    • 5 years ago
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    b (the constant term) is the y value where the line crosses the y axis.

  28. anonymous
    • 5 years ago
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    It is in y=mx+b already

  29. anonymous
    • 5 years ago
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    What is your m?

  30. anonymous
    • 5 years ago
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    Well Im not sure, the problem is matching up the graphs to the equation '

  31. anonymous
    • 5 years ago
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    No, I'm saying if you have an equation y = -2x y = -2x + 0 y = mx + b It is in slope intercept form.

  32. anonymous
    • 5 years ago
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    What is m?

  33. anonymous
    • 5 years ago
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    What is b?

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