# Writing Algebraic Expressions

Just like any language, math has a way to communicate ideas. An algebraic expression is a compact way of describing mathematical objects using a combination of numbers, variables (letters), and arithmetic operations namely addition, subtraction, multiplication, and division.

In other words, the three main components of algebraic expressions are numbers, variables, and arithmetic operations.

• NUMBERS OR CONSTANTS

Examples: $1$, $6$, $8$, $27$, $32$, etc.

• VARIABLES OR LETTERS

Examples: $x$, $y$, $a$, $h$, $p$, etc.

• ARITHMETIC OPERATIONS

Examples: $+$ (addition),  $-$ (subtraction) ,  $\times$ (multiplication) , $÷$ (division)

The following are easy examples that can help you get familiarized with the operations of addition, subtraction, multiplication, and division.

the sum of $x$ and $5$$x+5$

• Subtraction

the difference of $y$ and $3$$y-3$

• Multiplication

the product of $n$ and $2$$2n$

• Division

the quotient of $k$ and $7$${k \over 7}$

## Writing Algebraic Expressions Step-by-Step Examples

Let’s go over more examples.

Example 1: The sum of twice a number and $3$

Answer: Let variable $x$ be the unknown number. So twice a number means $2x$. The sum (use plus symbol) of twice a number and $3$ can be written as $2x+3$.

Example 2: The difference of triple a number and $5$

Answer: Let variable $y$ be the unknown number. So triple a number means $3y$. The difference (use minus symbol) of triple a number and $5$ should be written as $3y - 5$.

Example 3: The sum of the quotient of $m$ and $2$, and the product of $4$ and $n$.

Answer: In this case, the unknown numbers are already provided as $m$ and $n$. That’s one less thing to worry.

The key is to recognize that we are going to add a quotient and a product.

• the quotient of $m$ and $2$ is expressed as ${m \over 2}$
• the product of $4$ and $n$ is expressed as $4n$

Therefore, the sum of the quotient and product is ${m \over 2} + 4n$.

Example 4: The difference of the product of $7$ and $w$, and the quotient of $2$ and $v$.

Answer: In this case, the unknown numbers have been assigned with corresponding variables which are $w$ and $v$.

The key is to recognize that we are going to subtract the product by the quotient of some expressions.

• the product of $7$ and $w$ is expressed as $7w$
• the quotient of $2$ and $v$ is expressed as ${2 \over v}$

Therefore, the difference of the product and quotient is $7w - {2 \over v}$.

## Common Words or Terms to Mean Addition, Subtraction, Multiplication, and Division

Now, let’s go over some common words or phrases that describe the four arithmetic operations. It is critical that you know these words or phrases to be successful in writing or interpreting any given algebraic expression.

## Math Phrases into Algebraic Expressions

The key to learning is to study a LOT of examples!

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Algebraic Expressions Worked Examples