lesson 1

# Sets of Numbers

• The Set N of Natural Numbers

$${\rm{N = \{ 0,1,2,3,4, }}…{\rm{ \} }}$$

• The Set Z of Integers

$${\rm{Z = \{ }}…{\rm{ , – 3, – 2, – 1, 0,1,2,3, }}…{\rm{ \} }}$$

• The Set Z+ of Positive Integers

$${\rm{Z^ + = \{ 1,2,3,4, }}…{\rm{ \} }}$$

• The Set Q of Rational Numbers

$$Q = \{ x|x = {a \over b}\;where\;a,b \in Z,\;b \ne 0\}$$

• The Set I of Irrational Numbers

\eqalign{ & I = \{ x|x\;any\;real\;number & that & cannot\;be\;\exp ressed\;as\;a\;quotient\;of\;two\;{\mathop{\rm int}} egers\} \cr}

• The Set R of Real Numbers

$$R = \{ x|x\;can\;be\;written\;in\;decimal\;notation\}$$

• The Set C of Complex Numbers

The complex numbers are numbers of the form a + bi, where a and b are real numbers and i is the square root of -1.

$${\rm{i}}\;{\rm{ = }}\;\sqrt { – 1}$$