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Math Help - Help Please!!!

  1. #1
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    Help Please!!!

    This is a calculus problem! If anyone can help me please!!! Urgent!

    The problem says: (the pie I don't know how to write the symbol and squared is squaring the sin i don't know how to write it sorry)

    Let f be the function defined for pie/6 < x < 5pie/6 by f(x)= x +sin squared x.

    it says find:

    a.) Find all values of X for which f ' (x)= 1
    b.) find the x-coordinates of all minimum points of f. Justify your answer.
    c.) find the x-coordinates of all inflection points of f. Justiry your answer.

    Can someone please help me with this. It says show all your work! Please its urgent!!! Thankyou!!! Sorry again I don't know how to insert the symbols!
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  2. #2
    GAMMA Mathematics
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    Quote Originally Posted by mmkextreme_1 View Post
    This is a calculus problem! If anyone can help me please!!! Urgent!

    The problem says: (the pie I don't know how to write the symbol and squared is squaring the sin i don't know how to write it sorry)

    Let f be the function defined for pie/6 < x < 5pie/6 by f(x)= x +sin squared x.

    it says find:

    a.) Find all values of X for which f ' (x)= 1
    b.) find the x-coordinates of all minimum points of f. Justify your answer.
    c.) find the x-coordinates of all inflection points of f. Justiry your answer.

    Can someone please help me with this. It says show all your work! Please its urgent!!! Thankyou!!! Sorry again I don't know how to insert the symbols!
    f(x)= x +sin^2x

    f'(x) = 1 + 2sin(x)cos(x)

    1 =  1 + 2sin(x)cos(x)

    2sin(x)cos(x) = 0

    sin(x)cos(x) = 0

    Can you solve this?
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  3. #3
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    Quote Originally Posted by colby2152 View Post
    f(x)= x +sin^2x

    f'(x) = 1 + 2sin(x)cos(x)

    1 =  1 + 2sin(x)cos(x)

    2sin(x)cos(x) = 0

    sin(x)cos(x) = 0

    Can you solve this?

    no I don't really know what you did there and what would that be the answer to? Part A or what?
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  4. #4
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    Quote Originally Posted by colby2152 View Post
    f(x)= x +sin^2x

    f'(x) = 1 + 2sin(x)cos(x)

    1 =  1 + 2sin(x)cos(x)

    2sin(x)cos(x) = 0

    sin(x)cos(x) = 0

    Can you solve this?

    Actually come to think of it let me see am I suppose to do this:

    set sinx=0 and solve to where sin equals 0?

    and then set cosx=0 and solve for where cos equals 0?

    then where would f'(x)=1?

    and then how am I suppose to do b and c of that problem?

    I need urgent help on this pleaseee!!!!
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  5. #5
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    Quote Originally Posted by mmkextreme_1 View Post
    Actually come to think of it let me see am I suppose to do this:

    set sinx=0 and solve to where sin equals 0?

    and then set cosx=0 and solve for where cos equals 0?

    then where would f'(x)=1? Mr F says: For the values of x you get after solving cos x = 0 and sin x = 0.
    and then how am I suppose to do b and c of that problem?

    I need urgent help on this pleaseee!!!!
    (b) Solve f'(x) = 0. And to do that, you'll need to:
    1. Remember that 2 sin x cos x = sin(2x).
    2. Remember how to solve basic trig equations of the form sin(2x) = no.

    Then test the nature of the solutions you've found. You want the values of x that give minimum turning points. Then get the corresponding y-coordinates for these values of x.

    (c) Solve f''(x) = 0. Then test which of these give points of inflexion..

    There are a lot of different mathematical facts and skills you need to apply to successfully answer these questions. These assignment questions have exposed a lot of stuff you need to thoroughly review.
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  6. #6
    GAMMA Mathematics
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    Quote Originally Posted by mmkextreme_1 View Post
    Actually come to think of it let me see am I suppose to do this:

    set sinx=0 and solve to where sin equals 0?

    and then set cosx=0 and solve for where cos equals 0?
    You are right on target...

    Quote Originally Posted by mmkextreme_1 View Post
    then where would f'(x)=1?
    Look back at my work, and you will see I do this in the third line.

    Quote Originally Posted by mmkextreme_1 View Post
    and then how am I suppose to do b and c of that problem?

    I need urgent help on this pleaseee!!!!
    B) Solve for f'(x) = 0
    C) Solve for f''(x) = 0
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  7. #7
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    mmkextreme: I don't mean to be rude, but these problems are obviously beyond your knowledge base. For example, anyone who doesn't know how to solve sin(x)~cos(x) = 0 by the time they are studying Calculus is showing a serious flaw in their basic Math skills.

    I suggest you talk to your teacher about this and start some remedial work ASAP.

    -Dan
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