Math

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Given that the quadratic polynomial f(x)=3x^2+ax+b has real coefficients and f(x)=0 has a complex root 8+5i, what is the value of a+b?

  • Math -

    The other root must be 8-5i, so
    f(x) = 3(x-(8+5i))(x-(8-5i))
    = 3((x-8)^2 + 5^2)
    = 3(x^2-16x+89)
    = 3x^2 - 48x + 267

    a+b = 239

  • Math -

    219 sir

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