Number system (IX) set -5

What is the value of √(81)?

Which of the following is a rational number?

If x = 5, what is the value of 2x + 3?

Which of the following represents an irrational number?

What is the absolute value of -12?

Which of the following is an example of a perfect square?

What is 1/4 + 3/8?

Which number is the cube root of 27?

What is the value of | -5 + 3 |?

If a = 2 and b = 3, what is the value of a^2 + b^2?