Question

Select the correct description for each number set.
a) (25−−√, 9, −−−√64−−√)
b) ( -2.4, 0, 3.1, 81−−√)
c) (−23, 79, π2)
d) (12−−√, 11−−√, π)

Answer 1

a) Integers. sqrt(25)=5 and -sqrt(64) = -8, so (5, 9, -8) are all integers.

b) Rational numbers. -2.4 = -12/5, 0, 3.1 = 31/10 and sqrt(81)=9 are all rational.

c) Real numbers (a mixed set). -23 and 79 are integers (hence rational) but π^2 is irrational, so the set contains both rationals and irrationals — it is a set of real numbers.

d) Irrational numbers. sqrt(12), sqrt(11) (neither 12 nor 11 is a perfect square) and π are all irrational.