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anonymous

  • 4 years ago

What is the value of 1/2^-2x^-3y^5 for x = 2 and y = -4? 16 –4 –1/32 –16

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  1. anonymous
    • 4 years ago
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    Can you make a stab at it or do you need it explained from the start?

  2. anonymous
    • 4 years ago
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    i need it explained please...... sorry

  3. anonymous
    • 4 years ago
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    No problem! Why don't you start by writing it out using Draw, so I can understand the question better, please?

  4. anonymous
    • 4 years ago
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    ok no problem

  5. anonymous
    • 4 years ago
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    Great!

  6. anonymous
    • 4 years ago
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    |dw:1327955488648:dw|

  7. anonymous
    • 4 years ago
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    x = 2 and y = -4? so plug that in

  8. anonymous
    • 4 years ago
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    Great, let's do that.

  9. anonymous
    • 4 years ago
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    |dw:1327955697547:dw|

  10. anonymous
    • 4 years ago
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    and i can do the math with the exponents i just need help on what i do with the 1

  11. anonymous
    • 4 years ago
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    Well, show me what you get with thte exponents first

  12. anonymous
    • 4 years ago
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    Just the answer's fine, if you think it's right, otherwise we can go through the working if it's wrong

  13. anonymous
    • 4 years ago
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    2,048 for the exponents im not sure what to do with 1

  14. anonymous
    • 4 years ago
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    You;re a bit off with the exponents. Let's see your working out. Then we'll get onto the 1.

  15. anonymous
    • 4 years ago
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    Let's start with the first bit: What is this? |dw:1327956095456:dw|

  16. anonymous
    • 4 years ago
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    -4

  17. anonymous
    • 4 years ago
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    Not quite. How do negative exponents work?

  18. anonymous
    • 4 years ago
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    im not sure i was sick when ,y teacher explained this to me and this is off my make up work

  19. anonymous
    • 4 years ago
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    No problem, I'll explain it to you :D Btw "I don't know" is an excellent answer at any stage, don't be afraid of saying it!

  20. anonymous
    • 4 years ago
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    The rule for negative exponents is this:|dw:1327956265582:dw|

  21. anonymous
    • 4 years ago
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    Are you familiar with the general rule:|dw:1327956314617:dw| ?

  22. anonymous
    • 4 years ago
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    aha ok :) thank you yeah i am

  23. anonymous
    • 4 years ago
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    Well this just takes it a step further. 3^4=81, 3^3=27, 3^2=9, 3^1=3, 3^0=1.

  24. anonymous
    • 4 years ago
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    That much you understand already?

  25. anonymous
    • 4 years ago
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    yeah i do

  26. anonymous
    • 4 years ago
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    Great!

  27. anonymous
    • 4 years ago
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    You can see that each time, I reduced the exponent by 1, from 4 to 3 to 2 etc. And the answer got divided by three each time, so from 81 to 27 to 9 to 3 to 1.

  28. anonymous
    • 4 years ago
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    Does that make sense?

  29. anonymous
    • 4 years ago
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    Or shall I draw it using a picture, if that might help?

  30. anonymous
    • 4 years ago
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    yeah i understand what your saying

  31. anonymous
    • 4 years ago
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    Great! Then if I take it further, watch what happens: Reducing the exponent by 1, I get 3^-1, and dividing by three on the other side I get 1/3. This continues: 3^-2 = 1/9, 3^-3=1/27 etc. Which is why, as you can see, 3^-x=1/3^x

  32. anonymous
    • 4 years ago
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    Did that make sense or should I use draw?

  33. anonymous
    • 4 years ago
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    no it made sense i see what your sayinng

  34. anonymous
    • 4 years ago
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    Excellent! So now, can you tell me what 2^-2 is?

  35. anonymous
    • 4 years ago
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    (Or would you prefer to try the whole question yourself?)

  36. anonymous
    • 4 years ago
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    4

  37. anonymous
    • 4 years ago
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    Not quite. 2^2=4, so what is 2^-2 ?

  38. anonymous
    • 4 years ago
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    -4

  39. anonymous
    • 4 years ago
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    Nope, not that either :(

  40. anonymous
    • 4 years ago
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    What's the rule we just looked at, for negative exponents?

  41. anonymous
    • 4 years ago
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    0.25

  42. anonymous
    • 4 years ago
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    |dw:1327957142206:dw|

  43. anonymous
    • 4 years ago
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    Did you use your computer's calculator for that or work it out yourself?

  44. anonymous
    • 4 years ago
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    See if you can understand the picture I've drawn for you.

  45. anonymous
    • 4 years ago
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    i worked it out for myslef

  46. anonymous
    • 4 years ago
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    good. how?

  47. anonymous
    • 4 years ago
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    calculator :/

  48. anonymous
    • 4 years ago
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    THought so :(

  49. anonymous
    • 4 years ago
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    im a failure to life goodbye world im gonna kill myself

  50. anonymous
    • 4 years ago
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    The rule for negative indices is this:|dw:1327957460830:dw|

  51. anonymous
    • 4 years ago
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    No, don' tdo that!

  52. anonymous
    • 4 years ago
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    Look at the rule I've given you, do you understand what I've said?

  53. anonymous
    • 4 years ago
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    Ah well, well done for trying :)

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