The Real-Number System

Real Numbers

• In applications of algebraic concepts, we use real numbers to represent quantities such as distance, time, speed, area, profit, loss, and temperature.
• Some frequently used sets of real numbers and the relationships among them are shown below.

Important Phrases and Expressions:

Lowest Common Multiple:

Write down the LCM of 4 and 5

Step 1: Write down some multiples of 4  4, 8, 12, 16, 20, 24, 28

           Step 2: Write down some      multiples of 5 : 5, 10, 15, 20, 25, 30

Step 3: Check to see if there is a number that appears in both lists. If not write some more  multiples down.

Step 4: If there is more than one number that  (smallest) one. The LCM of 4 and 5 is 20.

Method (2):Prime factorization

To  do prime factorization.  Write down the number they have in common only once, then write down the leftover numbers.  Multiply them all together.

Practice:

Answers: 1)D   2)E   3)B