3/8 is rational. Rational numbers are numbers that can be written as a fraction. Irrational numbers cannot be expressed as a fraction.
The square roots of three are examples of irrational numbers.
You can not add irrational numbers. You can round off irrational numbers and then add them but in the process of rounding off the numbers, you make them rational. Then the sum becomes rational.
Integers are rational. In the set of real numbers, every number is either rational or irrational; a number can't be both or neither.
No. The easiest counter-example to show that the product of two irrational numbers can be a rational number is that the product of √2 and √2 is 2. Likewise, the cube root of 2 is also an irrational number, but the product of 3√2, 3√2 and 3√2 is 2.
Not necessarily. The cube roots of 4, 6 and 9 are all irrational (and different). But their product is 6, not just rational, but an integer.
The sum of the three can be rational or irrational.
Real numbers, imaginary numbers and irrational numbers are three kinds of numbers. Others are rational numbers, algebraic numbers and primes numbers. There are many more.