A probability problem by Ricardo Luiz Motta
The independent term "c" of the equation is chosen randomly among elements . What is the probability that the equation has real roots?
O termo independente "c" da equação x^2-3x+c=0.É escolhido aleatoriamente entre os elementos de {-1,0,1,2,3}.Qual é a probabilidade de essa equação vir a ter raízes reais?
The answer is 0.8.
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1 solution
The equation has real roots if the discriminant of the equation is not negative.
By choosing -1, 0, 1, and 2 for c you find the discriminant is non-negative. i.e. real roots exist for 4 of the 5 values provided in the set.
Hence probability is 4/5 or 0.8