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Math Help - Differention help

  1. #1
    age
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    Differention help

    Hi, I was wondering if you could help me out with a few problems

    1)log (3x+8x^3)
    2)3sqrr(2x-1)
    3)e^x.cosecx
    4)e^(4x+3)/4x+3
    5)find g'''(x) when g(x)=7x^3-2x^2+4x-8
    6)If x=sin(x) y= sec(x) find dy/dx
    7)x=t^2 y=2t + 1
    find the equation of the tangent at the point where t=2


    I ended up with
    1)24x^2 + 3/3x+8x^3
    2)2/3(2x-1)^-2/3
    3)-cosecxcotx.e^x + cosec.e^x
    4)4e^4x+3(4x+3)-4e^4x+3/(4x+3)^2
    5)42
    6)sec(x).tan(x)/cos(x)
    7)1/2x + 3

    are my answers correct?
    Thanks in advance
    Last edited by age; March 22nd 2011 at 10:53 PM.
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  2. #2
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    1. Assuming you meant (24x^2 + 3)/(3x + 8x^3), then yes, you are correct. Brackets are ESSENTIAL!

    2. Incorrect.

    3. Correct

    4. I suspect you have again not used brackets correctly. Please fix it so that I can read it.

    5. Correct

    6. What on earth are you using "deg" to represent?

    7. Correct.
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  3. #3
    age
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    Quote Originally Posted by Prove It View Post
    1. Assuming you meant (24x^2 + 3)/(3x + 8x^3), then yes, you are correct. Brackets are ESSENTIAL!

    2. Incorrect.

    3. Correct

    4. I suspect you have again not used brackets correctly. Please fix it so that I can read it.

    5. Correct

    6. What on earth are you using "deg" to represent?

    7. Correct.
    Thanks for the feedback

    my answer for question 4
    (4x+3).4e^4x+3 - 4e^4x+3/(4x+3)^2

    and how would i go about solving question 2 and 6?

    Thanks
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  4. #4
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    Assuming that your original function is [e^(4x+3)]/(4x+3) and your answer is [4(4x+3)e^(4x+3) - 4e^(4x+3)]/[(4x+3)^2], then you are correct. Brackets are NOT a luxury!
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  5. #5
    age
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    thanks for all your help
    Last edited by age; March 23rd 2011 at 01:25 PM.
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