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anonymous

  • 4 years ago

Find the limit as x approaches 4, using an algebraic method (not derivation). [sqrt(x^2-1)-sqrt(15)]/(x-4)

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  1. anonymous
    • 4 years ago
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    |dw:1327344927815:dw|

  2. anonymous
    • 4 years ago
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    Drawing is for clarification.

  3. anonymous
    • 4 years ago
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    multiply top and bottom by \[\sqrt{x^2-1}+15\]and you will get it quickly

  4. anonymous
    • 4 years ago
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    numerator will be \[x^2-16=(x+4)(x-4)\] cancel with the x - 4 in the denominator, then replace x by 4

  5. anonymous
    • 4 years ago
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    What about the denominator?

  6. anonymous
    • 4 years ago
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    So it will be (4+4)/(sqrt(15)+sqrt(15)

  7. anonymous
    • 4 years ago
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    That will equal 8/sqrt(30) which isn't the answer I found on wolfram or anything else. All other programs say the answer is 4/sqrt(15)

  8. myininaya
    • 4 years ago
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    you have a mistake in simplifying

  9. myininaya
    • 4 years ago
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    \[\frac{8}{2 \sqrt{15}} =\frac{4}{\sqrt{15}}\]

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