Closure in practice

Exercise and reference answers

Questions

1. Question

   Adding two rational numbers gives

   Choices

   1. always an integer
   2. a rational number
   3. an irrational number

   Correct choice

   a rational number

2. Question

   Multiplying two rational numbers gives

   Choices

   1. always a whole number
   2. an irrational number
   3. a rational number

   Correct choice

   a rational number

3. Question

   Closure under subtraction means

   Choices

   1. the difference is still rational
   2. the difference is positive
   3. the difference is an integer

   Correct choice

   the difference is still rational

Explanation