Repeating decimals are considered rational numbers because they can be represented as a ratio of two integers. If a number is terminating or repeating, it must be rational if a decimal is both non terminating and non repeating, the number is irrational.
So yes.
Answer: 
Step-by-step explanation:
For this exercise it is important to remember the multiplication of signs. Notice that:

In this case you have the following expression given in the exercise:

Then you can follow the steps shown below in order to solve it:
Step 1: You must solve the subtraction of the numbers 0,65 and 3,21. Then:

Step 2: Now you must find the product of the decimal numbers above. In order to do that you must multiply the numbers.
(As you can notice, both are negative, therefore you know that the product will be positive).
Then, you get that the result is the following:

The sequence is incrementing by

Therefore, the sixth number is

Which is 64.
Answer:
Since the value of f(0) is negative and the value of f(1) is positive, then there is at least one value of x between 0 and 1 for which f(x) =0.
Step-by-step explanation:
The equation f(x) given is:

For x = 0. the value of the expression is:

For x = 1, the value of the expression is:

Since the value of f(0) is negative and the value of f(1) is positive, then there is at least one value of x between 0 and 1 for which f(x) =0.
In other words, there is at least one solution for the equation between x=0 and x=1.