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  1. #1

    need help with algebra2 :]

    "You have a picture that is 12in by 16in that you will place on a mat and have framed. The mat will provide a border around the picture that is the same width all around the picture. If the mat and the picture together have a total area of 376 square inches, then determine how wide a border the mat provides
    (show work and round two decimal places)"

    so yeah,
    help me :/

    ___________
    if u dont get that, solve this

    x^4 + 8x^2 - 9 = 0

  2. #2

    Use a calculator.

    1st one, try (12+x) (16+x) = the area, which was 376 or something. then Solve for x.

  3. #3

  4. #4
    Old Merits
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    Re: need help with algebra2 :]

    Quote Originally Posted by untouchable
    if u dont get that, solve this

    x^4 + 8x^2 - 9 = 0
    (x^2 - 1) (x^2 + 9) = 0

    x^2 - 1 = 0
    x^2 = 1
    x = 1 or -1

    x^2 + 9 = 0
    x^2 = -9
    x = an imaginary number, dunno if you've covered that.

  5. #5

    ty, now try this one:

    "A type of mouse is introduced into a new habitat. The population of the mouse is given by
    P(t)= 0.00174t^4 - 0.02814t^3 + 0.06255t^2 + 3"

    a. How many mice were originally introduced?
    b. how many mice are present at t=6 months?

  6. #6
    Old Merits
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    Jesus just think about it. Put t=0 and t=6 into the equation. If you seriously can't put numbers into a calculator (this is nothing more difficult than that) then you should be at a special school.

  7. #7

    lol sorry algebra isnt my forte
    why im studying for finals :/


    16^2/3
    _______ over
    32^1/2

  8. #8
    Users Awaiting Email Confirmation
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    Hell, while we are asking for help with math...

    anti-derivative of cos^2(x) dx

    Driving me crazy

  9. #9

    Quote Originally Posted by Demosthenes11
    Hell, while we are asking for help with math...

    anti-derivative of cos^2(x) dx

    Driving me crazy
    The integral of (cos(x))^2 would be (sin(x))^3) / 3. The derivative of sin is cos, I'm pretty sure of that. So, if you take the deriviate of the answer I gave you, you will get the (cos(x))^2.

  10. #10

    Quote Originally Posted by untouchable
    lol sorry algebra isnt my forte
    why im studying for finals :/


    16^2/3
    _______ over
    32^1/2
    Is this a matter of simplifying it and keeping it in exponential form, or solving it altogether?

    16^2/3 is basically the cubed root of 16, then square that. 31^1/2 is saying the square root of 32.

  11. #11
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    derivative of sin^3(x)/3 is:

    sin^2(x) cos (x)

    due to the chain rule aka power rule

    I think I figured it out though

    cos^2(x) is equal to (1/2)(cos(2x)+1) because of the derivation of cos(x/2)


    Take the antiderivative of that and its (1/4)sin(2x)+(1/2)x+c

    Or am I wrong? :X

  12. #12

    ty again


    Quote Originally Posted by Cyprus
    Use a calculator.

    1st one, try (12+x) (16+x) = the area, which was 376 or something. then Solve for x.

    my friend said it should be 2x since theres 2 sides to the border thing

    but i still ended up with:
    (12+2x)(16+2x)=376
    192 + 24x + 32x + 4x^2 = 376
    4x^2 + 56x + 192 = 376
    4^2 + 56x - 184 = 0
    4(x^2 + 16x - 46) = 0

    yeah.. i also tried it this way..

    (12+2x)(16+2x)=376
    192 + 24x + 32x + 4x^2 = 376
    4x^2 + 56x + 192 = 376
    4x^2 + 56x = 184
    4x(x+14) = 184
    x = 46/x - x

    is there like a math forum somewhere so i stop bothering bg forums?

  13. #13

    Quote Originally Posted by Demosthenes11
    derivative of sin^3(x)/3 is:

    sin^2(x) cos (x)

    due to the chain rule aka power rule

    I think I figured it out though

    cos^2(x) is equal to (1/2)(cos(2x)+1) because of the derivation of cos(x/2)


    Take the antiderivative of that and its (1/4)sin(2x)+(1/2)x+c

    Or am I wrong? :X
    Chain rule and power rule aren't the same thing, but yeah, you were right about it being sin^2(x) cos(x), I was wrong in my first post :X.

    I'm not sure how cos^2(x) = (1/2)(cos(2x) +1) though. If you meant the derivative of cos^2(x), that would be 2(cos(x))(-sinx).


    I fucking hate calculus and I'm supposted to be studying history right now.

  14. #14

    Quote Originally Posted by untouchable
    ty again


    Quote Originally Posted by Cyprus
    Use a calculator.

    1st one, try (12+x) (16+x) = the area, which was 376 or something. then Solve for x.

    my friend said it should be 2x since theres 2 sides to the border thing

    but i still ended up with:
    (12+2x)(16+2x)=376
    192 + 24x + 32x + 4x^2 = 376
    4x^2 + 56x + 192 = 376
    4^2 + 56x - 184 = 0
    4(x^2 + 16x - 46) = 0

    yeah.. i also tried it this way..

    (12+2x)(16+2x)=376
    192 + 24x + 32x + 4x^2 = 376
    4x^2 + 56x + 192 = 376
    4x^2 + 56x = 184
    4x(x+14) = 184
    x = 46/x - x

    is there like a math forum somewhere so i stop bothering bg forums?
    I'm going to agree with your friend about the 2x. But after you solve it to the first thing you did, divide out the 4 so you just have the quadratic equation. From there do the quadratic formula or factor it.

  15. #15
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    cos(2x)=cos^2(x)-sin^2(x)

    cos(2x)=cos^2(x)-(1-cos^2(x))

    cos(2x)=2cos^2(x)-1

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

    (1/2)(cos(2x)+1)=cos^2(x)

  16. #16
    Hayleystrator
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    Bahamut

    I'd rather peel my nails off than take grade school math again.

  17. #17

    do your own homework

  18. #18

    Quote Originally Posted by Almaa
    do your own homework

  19. #19

    GUYS STOP!! YOU'RE KILLING OUR FRIEND TOTIEN!!!!

    Quote Originally Posted by Totien
    Whenever I see people quoting others without adding anything to the discussion, I die inside.
    8)

  20. #20

    Quote Originally Posted by aurik
    Quote Originally Posted by Almaa
    do your own homework
    take-home test >_________>
    (class is flunking pretty bad teacher felt sorry orz)

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