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waheguru

  • 4 years ago

Simplaify This 2x^-4y^-3(7x^3y^-2) PLEASE HELP ME

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  1. waheguru
    • 4 years ago
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    I dont understnad how???

  2. anonymous
    • 4 years ago
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    |dw:1327615451961:dw|

  3. anonymous
    • 4 years ago
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    a negative index = 1 / positive eg x^-2 = 1/x^2

  4. anonymous
    • 4 years ago
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    the answer can also be written as 14x^-1 y^-5 ( x^-1 = 1/x)

  5. waheguru
    • 4 years ago
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    I still doont understanr

  6. anonymous
    • 4 years ago
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    hmm - my time is limited at moment - try the khanacademy site wahe - its got a good reputation

  7. waheguru
    • 4 years ago
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    why is the 14 positive its -2 x 7 = -14

  8. JamesJ
    • 4 years ago
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    \[ 2x^{-4}y^{-3}(7x^3y^{-2}) \] this is your expression?

  9. waheguru
    • 4 years ago
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    the 7 is negavive

  10. JamesJ
    • 4 years ago
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    \[ 2x^{-4}y^{-3}(-7x^3y^{-2}) \] is this it?

  11. waheguru
    • 4 years ago
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    can u help me do this one \[4a^7b^5m^10(ten) (8a^9-b^-5m^2)+4a^7m^12/(2a^3bm^2)^5\]

  12. JamesJ
    • 4 years ago
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    wait. Do you have the answer to your first question or not?

  13. waheguru
    • 4 years ago
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    yea i just forgot to put the - sigh but i dont get the way jimmy drew it why was the 14 over the other things|dw:1327617362311:dw|

  14. JamesJ
    • 4 years ago
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    Let's try it one more time. Your question then is: Simply this expression \[ 2x^{-4}y^{-3}(7x^3y^{-2}) \] correct?

  15. waheguru
    • 4 years ago
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    the 2 is negative ---the first one

  16. waheguru
    • 4 years ago
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    What do we do now?

  17. JamesJ
    • 4 years ago
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    So it's this: \[ -2x^{-4}y^{-3}(7x^3y^{-2}) \] yes or no?

  18. waheguru
    • 4 years ago
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    yes

  19. JamesJ
    • 4 years ago
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    Right. First of all then, do you agree by the commutative property of multiplication, that we can reorder all of the terms and that \[ -2x^{-4}y^{-3}(7x^3y^{-2}) = (-2)7.x^{-4}x^3.y^{-3}y^{-2} \]

  20. waheguru
    • 4 years ago
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    Yes

  21. JamesJ
    • 4 years ago
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    Good. Now we need to simplify each set of terms appropriately. (-2)7 = -14 that's straight forward I hope. What about \[ x^{-4}x^3 \] what's that equal to?

  22. waheguru
    • 4 years ago
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    x\[x-1???\]

  23. waheguru
    • 4 years ago
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    x^-1

  24. JamesJ
    • 4 years ago
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    yes. And \[ y^{-3}y^{-2} \] is equal to what?

  25. waheguru
    • 4 years ago
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    y^-5

  26. JamesJ
    • 4 years ago
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    Yes, hence the answer is \[-14x^{-1}y^{-5} \] which we can also write as \[ \frac{-14}{xy^5} \] that make sense?

  27. waheguru
    • 4 years ago
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    I dont get the bottom part

  28. JamesJ
    • 4 years ago
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    By definition \[ x^{-1} \] means and is equal to \[ \frac{1}{x} \]

  29. waheguru
    • 4 years ago
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    Oh

  30. JamesJ
    • 4 years ago
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    Therefore also \[ y^{-5} = (y^5)^{-1} = \frac{1}{y^5} \]

  31. waheguru
    • 4 years ago
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    SO if it has a power of -2 then the numerator is also 2???

  32. JamesJ
    • 4 years ago
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    in the denominator, yes. For instance \[ 3^{-2} = \frac{1}{3^2} \] That makes good sense because, for example it makes this consistent: \[ 3 = 3^1 \] \[= 3^{3-2} \] \[ = 3^3.3^{-2} \] \[ = 3^3 \frac{1}{3^2} \] \[= 27 \frac{1}{9} \]

  33. waheguru
    • 4 years ago
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    k

  34. JamesJ
    • 4 years ago
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    that last expression is 27 times 1/9 which is of course equal to 3.

  35. JamesJ
    • 4 years ago
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    Therefore \[ -14x^{-1}y^{-5} = - \frac{14}{xy^5} \]

  36. waheguru
    • 4 years ago
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    Thankyou spoooooo much

  37. waheguru
    • 4 years ago
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    4a7b5m10(ten)(8a9−b−5m2)+4a7m12/(2a3bm2)5 can u help me with tis one

  38. waheguru
    • 4 years ago
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    \[4a7b5m10(ten)(8a9−b−5m2)+4a7m12/(2a3bm2)5\]

  39. JamesJ
    • 4 years ago
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    ok. good luck with your next one. Work it out patiently. Check it. Do it again. Iron out the errors. See if you can't figure it out. What's you've written is unreadable to me.

  40. waheguru
    • 4 years ago
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    oh ill write it again

  41. waheguru
    • 4 years ago
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    \[4a^7b^5m^10(ten)(8a^9-b^-5m^2)+4a^7m^12)))divide by (2a^3bm^2)\]

  42. JamesJ
    • 4 years ago
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    To get more than one thing in the exponent, use curly brackets. For example x^{10} \[ x^{10} \] To write a fraction, use \frac{a}{b} \[ \frac{a}{b} \]

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