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anonymous

  • one year ago

Please help me..... =*( Line A has slope of -5/3 and passes through the point (-2,7). What is the x-intercept of line A?

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  1. Zale101
    • one year ago
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    First, use the given infiltration to construct the equation of line A, then set y equals to zero and solve for x. The x's that you solved for are the x-intercepts.

  2. anonymous
    • one year ago
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    |dw:1439228461781:dw|

  3. Zale101
    • one year ago
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    You can use the point slope formula and plug all the given info in. Do you remember the point slope formula?

  4. anonymous
    • one year ago
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    I have a problem understanding where to put the numbers... In what cases do you replace it for Y and in what cases do u replace it for b?

  5. anonymous
    • one year ago
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    y=mx+b

  6. Zale101
    • one year ago
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    \(\Large y-y_1=m(x-x_1)\) Where x1,y1 is the given point and m is the slope

  7. Zale101
    • one year ago
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    That is the point slope formula ^^

  8. anonymous
    • one year ago
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    is there any way to solve the problem without the point slope formula? because the solution doesnt use it

  9. Zale101
    • one year ago
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    Or you can use y=mx+b Plug x,y by the given point and m for the slope Then solve for b After solving for b, you then go back and write y=mx+b again and plug in the y-intercept (b) and slope. Then, you have the equation solved.

  10. anonymous
    • one year ago
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    yea thats what i have a problem understanding... in what case do you use it for b and in what case do you use it for Y???????????

  11. Zale101
    • one year ago
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    All the matters is to construct the equation of line A so you can set y to zero and solve for the x-intercept. There's two ways you can do it.

  12. anonymous
    • one year ago
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    i really need to understand that for future problems

  13. Zale101
    • one year ago
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    Yes, i understand. |dw:1439228871702:dw|

  14. anonymous
    • one year ago
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    then what about the Y what is the y then?

  15. Zale101
    • one year ago
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    m and b (the slope and the y-intercept) are constants. Meaning, when writing the equation, the numbers are giving for them. But x and y is changing. It does not have a constant number. the x is the input and any numbers from the x-axis can be plugged into it. There's no constant, specific number to plug. It is changing. Same goes to y. Y is changing and it is the output. You can plug whatever number you want from the y-axis. There's no specific number.

  16. Zale101
    • one year ago
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    For example. The graph y=x |dw:1439229116348:dw|

  17. anonymous
    • one year ago
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    so when it says (2,7) is on the number line does that mean it's a constant?

  18. Zale101
    • one year ago
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    But when you have a slope and the y-intercept (m and b) then the line changes position or shifts from y=x.

  19. anonymous
    • one year ago
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    So can you tell me how to spot the constant?

  20. Zale101
    • one year ago
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    That means that line A passes through this point (2,7) as well as many many other points. But this point can locate where the line is. You can think of it as a pin point on the graph and you can draw a line that passes through it. Of course, you can't draw a line from nowhere, you have to be given an info about the slope so we can understand what is the steepness of the line, does it have any or it does not. But it has, and the slope is already given to you. It is -5/3.

  21. Zale101
    • one year ago
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    The only constants are the slope (m) and the y-intercept (b). A point is not a constant on the equation because (x,y) keeps changing. (2,7) is just a point that we are giving the info of that the line passes through.

  22. Zale101
    • one year ago
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    Makes sense? Can we do some math now?

  23. anonymous
    • one year ago
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    oh okay so do we use (-2,7) to find the constant?

  24. Zale101
    • one year ago
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    Yes!! :D

  25. anonymous
    • one year ago
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    oh okay and 7 is the b intercept right?

  26. Zale101
    • one year ago
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    Nopes. 7 is a y-value that the pin point is located on. (2,7) where x=2 and y=7 is just a pin point ion the graph that gives us a sense where the line is positioned.

  27. anonymous
    • one year ago
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    oh okay

  28. Zale101
    • one year ago
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    Don't think of y-interpret as any y-value it is a y-value where the line crosses the y-intercept. A y-intercept will always have x as 0. If (2,7) was (0,7) then (0,7) would be the y-intercept. An example of y-intercept i'm going to show on a made up line.|dw:1439229765311:dw|

  29. anonymous
    • one year ago
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    oh okay i got it

  30. Zale101
    • one year ago
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    Good. Can you construct the equation now?

  31. anonymous
    • one year ago
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    |dw:1439229923659:dw|

  32. Zale101
    • one year ago
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    |dw:1439230074071:dw||dw:1439230059277:dw|

  33. anonymous
    • one year ago
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    oh okay so use the 2

  34. Zale101
    • one year ago
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    y=mx+b there's an x and a y in this formula. We can't just discard the x like that. We have to use the point (2,7) and plug in for x and y in here. Also, we can't discard the 2 in (2,7) :)

  35. anonymous
    • one year ago
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    |dw:1439230149474:dw|

  36. Zale101
    • one year ago
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    |dw:1439230219311:dw|

  37. anonymous
    • one year ago
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    so whats the next step?

  38. Zale101
    • one year ago
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    Now, we have the two constants m=-5/3 and b=31/3 So, y=mx+b the equation is y=(-5/3)+31/3|dw:1439231431455:dw|

  39. Zale101
    • one year ago
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    The next step is to find the x-intercept. How would you do that?

  40. anonymous
    • one year ago
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    no we did it wrong

  41. anonymous
    • one year ago
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    it's suppoed to be -5/3(-2) not positive 2

  42. anonymous
    • one year ago
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    so it's -5/3+11/3

  43. anonymous
    • one year ago
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    -5/3x+11/3

  44. Zale101
    • one year ago
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    Correct. when you said "so when it says (2,7) is on the number line does that mean it's a constant?" i thought it was (2,7), i didn't go back and check what it was originally.

  45. anonymous
    • one year ago
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    how come this works?

  46. anonymous
    • one year ago
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    |dw:1439231685078:dw|

  47. Zale101
    • one year ago
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    What works?

  48. anonymous
    • one year ago
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    |dw:1439231764295:dw|

  49. Zale101
    • one year ago
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    |dw:1439231837457:dw||dw:1439231907266:dw||dw:1439231951916:dw||dw:1439232046132:dw|

  50. Zale101
    • one year ago
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    pardon my mouse handwriting

  51. anonymous
    • one year ago
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    it's ok i get it now thanks you

  52. Zale101
    • one year ago
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    Anytime

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