Answer: Choice B
Rational x Irrational = Irrational
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Reason:
6 = a rational number
3pi = an irrational number
18pi = an irrational number
Anything involving pi is irrational. The value 6 is rational because 6 = 6/1.
pi is irrational since we cannot write it as a ratio of two integers. We can get approximations like 22/7, but we can't nail down the exact value of pi with a fraction.