UNIT 1

 

Text One 

 

 

a = b b = c   a = c	a is equal to b b is equal to c Therefore a is equal to c	a = b b ¹ d   a ¹ d	a is equal to b b is not equal to d Therefore a is not equal to d
a & b a = b	a and b a and b are equal	c & d c ¹ d	c and d c and d are not equal

 

Text One

 

If a is equal to b and if b is equal to c, then a is equal to c.

If a and c are equal and if b and d are not equal, then a and d are not equal.

If a and b are equal and if b and c are equal, then a and c are equal. 

 

Exercise: Correct or incorrect? 

1. If a is equal to b, then b is equal to a.

2. If a is not equal to b, then b is equal to a.

3. If a is equal to b and b is equal to c, then c is equal to a.

4. If a is not equal to c, then c is equal to a. 

 

Text Two

 

3 a a = 3 b = 1 c = 1 b = c

Three is a number. a is a letter. It is a name. It is a name for a number. The number is 3. b and c are two names for the same number. The number is 1. If b is equal to c, then b and c are names for the same number. If b and c are names for the same number, then we write: b = c. We write b = c if and only if b and c are names for the same number. If b is equal to c, then c is equal to b.

 

Two numbers, a and b, are equal and we write a = b if and only if a and b are names for the same number.  

 

Exercise: Correct or incorrect?

1. Two numbers, a and b, are not equal if they are names for the same number.

2. If two numbers, a and b, are equal, then a and b are not names for the same number.

3. If a and b are names for the same number, then a = b.

4. If a and b are not names for the same number, then a ¹ b.