Math

how many roots does this polynomial have: f(x) = 5x^3 + 8x^2 -4x + 3

and

Of the possible rational roots, which ones are roots: ±1, ±(1/5), ±3, ± (3/5)

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  1. According to the Fundamental Theorem of Algebra,
    5x^3 + 8x^2 -4x + 3 =0 will have 3 roots, at least one of which must be real.
    testing for x = 1
    5 + 8 - 4 + 3 ≠ 0
    testing for x = -1
    -5 + 8 + 4 - 3 ≠ 0

    tried the others, none worked, did not test the complex ones
    Then tried Wolfram, go this
    http://www.wolframalpha.com/input/?i=solve+5x%5E3+%2B+8x%5E2+-4x+%2B+3+%3D0

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