Question:
Let a be a rational number and b be an irrational number. Is ab necessarily an irrational number? Justify your answer with an example.
Solution:
a be a rational number and b be an irrational number then ab necessarily will be an irrational number.
Example: 6 is a rational number but $\sqrt{5}$ is irrational. And $6 \sqrt{5}$ is also an irrational number.