State whether the given statement is ture or false.
(i) The sum of two rationals is always rational.
(ii) The product of two rationals is always rational.
(iii) The sum of two irrationals is always an irrational.
(iv) The product of of two irrationals is always an irrational.
(v) The sum of a rational and an irrational is irrational.
(vi) The product of a rational and an irrational is irrational.
Sol:
(i) True
(ii) True
(iii) False
Counter example: 2 +3–√3 and 2 –3–√3 are two irrational numbers. But their sum is 4, which is a rational number.
(iv) False
Counter example: 23–√3 and 43–√3 are two irrational numbers. But their product is 24, which is a rational number.
(v) True
(vi) True