1 - Calcular o valor numérico das expressões algébricas: a) xs - x4 + 5, para x = 2
b) x3 - 2.x + 1, para x = 3​

There are 23 total marbles (9 red, 7 white, and 7 blue).  You want to select 4 marbles randomly without replacement.  We want to know the probability of selecting 4 red marbles.

In this case, we have 3 different colors.  By the formula (1 + 1 + 1)n = 3n, we can see how many possible outcomes of selecting 4 marbles randomly.  Let n = 4.

There are 81 possible outcomes.  We want to see which one has 4 red marbles.  Only 1 possible outcome will give us that.

Therefore, P(4 red marbles) = 1/81 ≈ 0.01235