Results 1 to 4 of 4

Math Help - I need fast HELP

  1. #1
    Newbie
    Joined
    Jan 2006
    Posts
    17

    I need help with these fast HELP!!!!!

    amount of natural gas is proportional to oxygen consumed. 24.0 kg of Oxygen is
    consumed in burning 15 kg of gas how much air 23% oxygen by wieght is consumed to burn 50 kg

    a.80 kg
    b 345 kg
    c. 31.3 kg
    d. 135 kg





    4.Which of the following expressions would help estimate the value of:
    Which of the following expressions would help estimate the value of:
    [IMG]



    a.36
    b.29.25
    c.t
    d.43

    5.During each microsecond the current in an electric circuit decreases by 9.3%. If the initial current is 2.45 mA, what will the current be after 22 microseconds?

    0.286 mA
    0.496 mA
    0.121 mA
    1.24 mA



    7.The sales S of a product as a function of the time t (in weeks) is given by S = [2300 (5t + 1)]/(2t + 5). Find the instantaneous rate of change of S with respect to t for t = 9 weeks.

    125
    51
    900
    100
    Last edited by jaycas21; August 6th 2006 at 10:52 AM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Global Moderator

    Joined
    Nov 2005
    From
    New York City
    Posts
    10,616
    Thanks
    10
    2. y= 5x^2 sqrt (x+1) find dx/dy
    Product rule,
    y'=(5x^2)'\sqrt{x+1}+(5x^2)(\sqrt{x+1})'
    Thus,
    y'=10x\sqrt{x+1}+\frac{5x^2}{2\sqrt{x+1}}
    Thus,
    y'=5x\sqrt{x+1}\left(2+\frac{x}{2(x+1)}  \right)
    6.
    Find the slope of the tangent to the curve of y = ln (25x + 3) at x = 2.

    a.0.47
    b.0.50
    c.1.2
    d.2.5
    y'=\frac{25}{25x+3}---> By chain rule,
    At x=2
    y'=\frac{25}{25(2)+3}
    Thus,
    y'\approx .47



    8.Find the center and radius of the circle: x2 + y2 - 18y = -17

    Center = (9,0), r = - 8
    Center = (1,8), r = 9
    Center = (8,1), r =9
    Center = (0,9), r = 8
    You need to "complete-the-square".
    x^2+(y^2-18y+81)-81=-17
    Thus,
    (x-0)^2+(y-9)^2=64=8^2
    Thus,
    \mbox{center }=(0,9)
    \mbox{radius }=8
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Eater of Worlds
    galactus's Avatar
    Joined
    Jul 2006
    From
    Chaneysville, PA
    Posts
    3,001
    Thanks
    1
    #3. F(x)=kx

    25=(20-10)k

    k=\frac{5}{2}

    \int_{0}^{5}\frac{5}{2}xdx
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by jaycas21
    amount of natural gas is proportional to oxygen consumed. 24.0 kg of Oxygen is
    consumed in burning 15 kg of gas how much air 23% oxygen by wieght is consumed to burn 50 kg

    a.80 kg
    b 345 kg
    c. 31.3 kg
    d. 135 kg





    4.Which of the following expressions would help estimate the value of:
    Which of the following expressions would help estimate the value of:
    [IMG]



    a.36
    b.29.25
    c.t
    d.43

    5.During each microsecond the current in an electric circuit decreases by 9.3%. If the initial current is 2.45 mA, what will the current be after 22 microseconds?

    0.286 mA
    0.496 mA
    0.121 mA
    1.24 mA



    7.The sales S of a product as a function of the time t (in weeks) is given by S = [2300 (5t + 1)]/(2t + 5). Find the instantaneous rate of change of S with respect to t for t = 9 weeks.

    125
    51
    900
    100
    Put new questions in a new post or better yet a new thread.

    DONT edit an existing post deleting the original questions and replacing them
    with new questions.

    RonL
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. need help fast
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: June 25th 2008, 12:53 PM
  2. Need help fast!
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: May 8th 2008, 02:28 PM
  3. Need help fast
    Posted in the Algebra Forum
    Replies: 1
    Last Post: April 23rd 2008, 12:41 PM
  4. Need help fast
    Posted in the Statistics Forum
    Replies: 1
    Last Post: July 20th 2007, 06:30 PM
  5. Can someone help me fast?
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: April 27th 2005, 11:54 AM

Search Tags


/mathhelpforum @mathhelpforum