Expressions

An expression is a mixture of numbers, letters and symbols (+, - , · …) that doesn’t include the = symbol.

               3 x - 5                     (a + b)²

 

To substitute in an expression is to put numbers in place of letters.

 

The value of an expression is the answer you get after substituting numbers for letters:

     the value of 3 x + 5 is 14 if x = 3

 

 

Exercise: calculate the value after substituting x = 5 in these expressions:

 

 

 

Solutions: a) 1; b) 16; c) 5