Algebraic language

# Expressions

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

3x-5 (a+b)^{2}

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

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

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

**Exercise**: Find an algebraic expression for these sentences:

a) The double of a number plus five.

b) The double of a number, plus five.

c) Half a number minus eight.

d) The square of the double of a number.

Solutions: a) 2·(x + 5); b) 2x + 5; c) (x-8)/2; d) (2x)^{2}

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