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Math Help - !?!?

  1. #1
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    !?!?

    Solve the equation

    x^2+4x=3

    should I move the 3 to the left so that I can factor it or is there another way?!

    Also how do I get from 4n^2=-8n-1 to {\frac{-2-\sqrt{3}}{2},\frac{-2+\sqrt{3}}{2}}


    Thanks!!
    Last edited by Morzilla; December 16th 2007 at 03:10 PM.
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  2. #2
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    Quote Originally Posted by Morzilla View Post
    Solve the equation x^2+4x=3
    should I move the 3 to the left so that I can factor it or is there another way?!
    To move something we must be able to pick it up.
    How does one pick up a number?
    Do you mean add to both sides of the equation?
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  3. #3
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    Quote Originally Posted by Plato View Post
    To move something we must be able to pick it up.
    How does one pick up a number?
    Do you mean add to both sides of the equation?

    hmmmm....sorry, I don't quite understand about picking up numbers.

    yes, so that it'll look like this;

    = x^2+4x-3=3-3

    = x^2+4x-3=0


    thanks
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  4. #4
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    GOOD.
    We know that we can add the same (-3) to both sides of then equation.
    You are correct.
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  5. #5
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    use the quadratic forumula:

    x = \frac{ -b \pm \sqrt{b^2 - 4ac} }{2a}

    where:

    ax^2 + bx + c = 0
    Last edited by incyt3s; December 16th 2007 at 05:03 PM.
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  6. #6
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    Quote Originally Posted by Plato View Post
    GOOD.
    We know that we can add the same (-3) to both sides of then equation.
    You are correct.
    Ok, now that I have x^2+4x-3=0 I need to factor it out no? But I couldn't, because two numbers that when multiplied together to get -3 cannot give me +4. Since the signs are the same in x^2+4x-3=0. So then what can I do here!?

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  7. #7
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    Quote Originally Posted by incyt3s View Post
    use the quadratic forumula:

    x = \frac{ -b \pm \sqrt{b^2 - 4ac} }{2a}

    where:

    ax^2 + bx + c = 0
    LOL how funny, there is another post on this formula and here it's being applied!

    I will look onto the other post. I am still trying to figure out that formula!!!

    Thanks

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  8. #8
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Morzilla View Post
    Ok, now that I have x^2+4x-3=0 I need to factor it out no? But I couldn't, because two numbers that when multiplied together to get -3 cannot give me +4. Since the signs are the same in x^2+4x-3=0. So then what can I do here!?

    quadratic formula. use it (or completing the square) when you can't factor something nicely
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  9. #9
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    Quote Originally Posted by Jhevon View Post
    quadratic formula. use it (or completing the square) when you can't factor something nicely
    Until I wrote down the quadratic formula I had not realized that yes, we used this formula in class! now it's slowly coming back to me, this is where

    a=x^2

    b=+4x

    c=-3

    and then we plug it into the formula, right?!

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  10. #10
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Morzilla View Post
    Until I wrote down the quadratic formula I had not realized that yes, we used this formula in class! now it's slowly coming back to me, this is where

    a=x^2

    b=+4x

    c=-3

    and then we plug it into the formula, right?!

    not exactly. a,b, and c are the COEFFICIENTS. thus, a = 1, b = 4 and c = -3
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  11. #11
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Morzilla View Post
    I will look onto the other post. I am still trying to figure out that formula!!!
    are you familiar with the method of completing the square? if so, try to derive the formula yourself by solving the general ax^2 + bx + c = 0 by completing the square.

    until then, just memorize the formula, it's not as hard as it may seem, and i know, my memory is horrible
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  12. #12
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    Quote Originally Posted by Jhevon View Post
    are you familiar with the method of completing the square? if so, try to derive the formula yourself by solving the general ax^2 + bx + c = 0 by completing the square.

    until then, just memorize the formula, it's not as hard as it may seem, and i know, my memory is horrible
    Thanks!!!
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