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Math Help - Difference quotient

  1. #1
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    Difference quotient

    F(x)= sqrt (x+1).

    Formula: F(x+h) - F(x) / h

    i cant seem to do this problem. i keep getting it wrong. so please help me
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  2. #2
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    Quote Originally Posted by lsnyder View Post
    F(x)= sqrt (x+1).

    Formula: F(x+h) - F(x) / h

    i cant seem to do this problem. i keep getting it wrong. so please help me
    chances are your problem lies in finding f(x + h)

    post what you think it is
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  3. #3
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    i keep writing out to this:

    sqrt(x+h+1) - sqrt(x+1) / h.


    after that i get lost and come up with random answers
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    Quote Originally Posted by lsnyder View Post
    i keep writing out to this:

    sqrt(x+h+1) - sqrt(x+1) / h.


    after that i get lost and come up with random answers
    ok, good so far. from here, the trick is to multiply by the conjugate of the numerator over itself, then simplify

    \frac {\sqrt{x + h + 1} - \sqrt{x + 1}}h \cdot \frac {\sqrt{x + h + 1} + \sqrt{x + 1}}{\sqrt{x + h + 1} + \sqrt{x + 1}}

    can you take it from here?
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  5. #5
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    so is it:

    x+h+1-x-1 / (h sqrt(x+h+1) + sqrt(x+1)

    this doesn't look right to me. and this is online homework, which i keep getting the wrong answer
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by lsnyder View Post
    so is it:

    x+h+1-x-1 / (h sqrt(x+h+1) + sqrt(x+1)

    this doesn't look right to me. and this is online homework, which i keep getting the wrong answer
    well, if you type it here like you type it there, of course you're wrong. you have incorrect use of parentheses here. (and not that the numerator simplifies to h--which cancels with the h in the denominator)
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    can u see this? if so, its the original problem, it might make more sense
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by lsnyder View Post


    can u see this? if so, its the original problem, it might make more sense
    nope, can't see anything
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  9. #9
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    okay well thanks for trying anyways.
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  10. #10
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    Quote Originally Posted by lsnyder View Post
    okay well thanks for trying anyways.
    just try to simplify from where you left off, and get your parentheses right
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