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    hi,

    need to find x, but i cant seem to solve it using quadratic formula, any other method?

    x^2 - 2x + 3 = 0

    help!! thanks
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    No real solutions, if you use the quadratic formula you will see that you get the square root of -8 which is about 2.82i. Perhaps you have the quadratic wrong if you could not see that?
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    to see if something has a double root, 2 unique roots, or no real roots
    use the discriminant!
    if it only solves for the complex numbers, ensure that your solutions match up with the function of definition!!

    D= b^2 - 4ac
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    (Original post by mir3a)
    which are two numbers which multiply to give +3, but add t give -2....
    i've tried the ones i can think of :/
    -1 and 3 , no
    -3 and 1 , no
    -3 and -1 , no
    -2 and 1 , no
    -1 and 2 , no
    3 and -5 , no

    :?
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    you can also try completing the square?
    that helped me alot with solving quadratics
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    If you put it into a calculator or program for the formula, it will probably tell you you are giving it an error due to the root part being negative (b^2 - 4ac). However, it actually comes to the square root of -8, which, when divided by 2 as in the formula, gives root 2 i, so the overall solution is 1 plus or minus iroot2. If in doubt, put it into wolfram alpha.
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    Ive got the quadratic from this, it is correct? x^2 - 2x + 3 = 0

    (log_{18}x)^2-2log_{18}x+log_{18}3=0
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    you will still get complex answers tho becoz the discriminant is less than 0!
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    lol no real rooots!!!! my friend you need some i's!
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    (Original post by dream123)
    Ive got the quadratic from this, it is correct? x^2 - 2x + 3 = 0

    (log_{18}x)^2-2log_{18}x+log_{18}3=0
    no that isn't correct

    you must work out log_{18}3 (~0.38)

    then add that into the equation to get x^2 - 2x + 0.38 = 0

    then use quadratic formula to solve for x
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    (Original post by dream123)
    Ive got the quadratic from this, it is correct? x^2 - 2x + 3 = 0

    (log_{18}x)^2-2log_{18}x+log_{18}3=0
    Here's your problem
    Use a substitution of y=\log_{18} x to get:
    y^2-2y+\log _{18} (3) = 0
    Solve this for y and then solve for x. This has a real solution.
 
 
 
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