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anonymous

  • 4 years ago

What is the sum of the roots of the polynomial shown below? f(x)=3x^3+12x^2+3x-18

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  1. agreene
    • 4 years ago
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    set the equation equal to 0 to find the roots, you should find x= -3, -2, 1 are the roots sum (add) the roots: (-3)+(-2)+1= -4

  2. anonymous
    • 4 years ago
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    you can also do this without finding the roots (in case they are harder to find than here)

  3. anonymous
    • 4 years ago
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    if you have \[ax^3+bx^2+cx+d=0\] sum of the roots is \[-\frac{b}{a}\] and here you see that \[-\frac{b}{a}=-\frac{12}{3}=-4\]

  4. anonymous
    • 4 years ago
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    produce of the roots (not that you asked) is \[-\frac{d}{a}\] in case you need that one. if all you need is product and sum, you do not need to find the roots, and in some cases finding the roots may be very hard

  5. anonymous
    • 4 years ago
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    *product

  6. agreene
    • 4 years ago
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    I had forgotten all of that, thanks satellite.

  7. anonymous
    • 4 years ago
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    yw

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