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lexy148

  • one year ago

How do you graph and solve for y= square root x-2 if the x points are 0,-1,-2,1,2

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  1. jim_thompson5910
    • one year ago
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    is the equation this? \[\Large y = \sqrt{x-2}\] or this?\[\Large y = \sqrt{x}-2\]

  2. lexy148
    • one year ago
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    the 1st one

  3. lexy148
    • one year ago
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    @jim_thompson5910

  4. jim_thompson5910
    • one year ago
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    if we replace x with 0, what result do you get \[\Large y = \sqrt{x-2}\] \[\Large y = \sqrt{0-2}\] \[\Large y = ???\]

  5. lexy148
    • one year ago
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    -2 ?

  6. jim_thompson5910
    • one year ago
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    you'll have \[\Large \sqrt{-2}\] BUT you cannot take the square root of a negative number. The result isn't a real number. So the calculator should say NAN or undefined or something

  7. jim_thompson5910
    • one year ago
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    did you type in `sqrt(0-2)` or `sqrt(-2)` into your calculator?

  8. lexy148
    • one year ago
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    yeah thats what it said when i did it in the calculator

  9. jim_thompson5910
    • one year ago
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    so because of this error, we don't include x = 0 in the domain

  10. lexy148
    • one year ago
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    i typed sqrt -2 not 0-2

  11. jim_thompson5910
    • one year ago
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    which calculator are you using?

  12. lexy148
    • one year ago
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    we wouldnt include any negative numbers in sqrt then

  13. jim_thompson5910
    • one year ago
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    yes you cannot have negative numbers under the square root eg: \(\Large \sqrt{-1}\) is not allowed

  14. lexy148
    • one year ago
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    a scientific calculator

  15. jim_thompson5910
    • one year ago
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    ok, what happens when you replace x with -1 instead of 0? what result do you get?

  16. lexy148
    • one year ago
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    ok so i wot put any negatives then thx

  17. lexy148
    • one year ago
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    i get -3

  18. jim_thompson5910
    • one year ago
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    the goal is to have x-2 never be negative so we can force it to be 0 or positive, ie force it to be greater than or equal to 0 \[\Large x-2\ge 0\] solve for x to get \[\Large x\ge 2\] so you are allowed to input values of x that are either 2 or larger than 2

  19. jim_thompson5910
    • one year ago
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    you'll find that \[\Large \sqrt{-3}\] isn't a real number. So x = -1 isn't allowed to be an input either

  20. lexy148
    • one year ago
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    ok i see so only numbers 2 or more, no negatives

  21. jim_thompson5910
    • one year ago
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    yep

  22. jim_thompson5910
    • one year ago
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    if x = 2, then what is the value of y?

  23. lexy148
    • one year ago
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    ok thank you and how would you sqrt 0 since 2-2 is 0

  24. jim_thompson5910
    • one year ago
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    the square root of 0 is 0

  25. jim_thompson5910
    • one year ago
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    your calculator should be able to calculate that if not, then use this calculator http://web2.0calc.com/

  26. lexy148
    • one year ago
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    nevermind i got it

  27. jim_thompson5910
    • one year ago
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    ok one more: if x = 6, then what is the value of y?

  28. lexy148
    • one year ago
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    thank you for helping me :)

  29. lexy148
    • one year ago
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    it would be 4

  30. jim_thompson5910
    • one year ago
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    the `x-2` part is 4 when x = 6 but I want the value of y \[\Large y = \sqrt{x-2}\] \[\Large y = \sqrt{6-2}\] \[\Large y = \sqrt{4}\] \[\Large y = ??\]

  31. lexy148
    • one year ago
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    oh srry it would be 2

  32. jim_thompson5910
    • one year ago
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    correct, so when x = 6, the value of y is y = 2 that means we have the point (6,2) earlier you found that when x = 2, the value of y was y = 0 so the point (2,0) You make a table of x,y values and plot each ordered pair as a point on the xy grid. Once you have enough points, you can draw a curve through them all to complete the graph

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