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Posted by on Thursday, June 12, 2008 at 12:25pm.

Quadratic Formula

Using +/- for plus or minus
Using \/ radical sign

*****************_________
Formula: -b +/- \/b^2-4ac
********____________________

*****************2a

Equation:

x^2 - 25 = 0

Books says answer is 5 and -5. I can get the 5. I do not get the -5.

  • Algebra - , Thursday, June 12, 2008 at 12:42pm

    I don't understand.

    Didn't you post the formula with a +/- ?

    so in your equation x^2 - 25 = 0
    a = 1
    b = 0
    c = -25

    so x = (0 ±√(0-4(1)(-25))/2
    = ±√100 / 2
    = ±10/2
    = ±5

    of course the easier way would be to write the equation as
    x^2 = 25 , then
    x = ±√25 = ±5

  • Algebra - , Thursday, June 12, 2008 at 12:48pm

    Yes I did post it with a +/- representing plus or minus the number.

    How were you about to show the +- with the minus sign uder the the plus sign?

    I looked at the answer you provided I think I can see my error. I was taking 0 for C not the 25. I remember now that C has to be a number without a variable next to it.

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