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algebra

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can someone show me how to solve this the instructions are for me to solve by the quadriatic formula is this really 8 grade math im confused im trying to help my daughter tammi and i have never run across this before

X^2 + 9=0

  • algebra - ,

    If the instructions are to solve by the quadratic formula, then this topic could be in grade 8 depending in what country you live.
    for any equation of the form
    ax^2 + bx + c = 0,
    x = (-b ± √(b^2-4ac) )/(2a)
    for your x^2 +9 = 0
    a = 1, b = 0 , and c = 9

    x = (0 ± √(0-36)/2
    = ± √-36/2
    = 3i , where i = √-1 , if she has studied complex numbers
    or
    there is no solution in the set of real numbers since we cannot take the square root of a negative number

    could be done without the formula.....

    x^2 + 9 = 0
    x^2 = -9
    x = ± √-9 = ± 3i as before

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