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Math Help - Dice

  1. #1
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    Dice

    Consider the equation x squared + kx + 1 = 0. A single fair die is rolled to determine the value of the middle coefficient, k. The value for k is the number of dots on the upper face of the die. What is the probability that the equation will have real, unequal roots? Is the answer 2/3's a chance? Thanks!
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  2. #2
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    Quote Originally Posted by jarny View Post
    Consider the equation x squared + kx + 1 = 0. A single fair die is rolled to determine the value of the middle coefficient, k. The value for k is the number of dots on the upper face of the die. What is the probability that the equation will have real, unequal roots? Is the answer 2/3's a chance? Thanks!
    Correct, jarny!

    We know the equation will have real, unequal roots when b^2 - 4*a*c > 0.

    k^2 - 4*1*1

    k^2 - 4

    k has to be greater than 2, and as you suggested, the probability of this occuring is 2/3. (Have to get a 3, 4, 5, 6 = 4/6 or 2/3)
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