Variables and Algebraic Expressions - Examples, Exercises and Solutions

Understanding Variables and Algebraic Expressions

Complete explanation with examples

When a problem is presented to us in writing, we can convert it into mathematical language (also called algebraic language) by transforming it into an algebraic expression. But what are algebraic expressions?

Variable: This is a letter that represents a numerical value, for example X X or Y Y . This letter refers to an unknown numerical value that we must work out. For example: if X+5=8 X+5=8 , then we can conclude that the numerical value of X X is 3 3 .

An algebraic expression is a combination of numbers and letters (representing unknown numbers) that includes operations such as addition, subtraction, multiplication, division, etc.

Each element of an algebraic expression is called an algebraic term, be it a variable, a constant, or a combination of a coefficient and one or more variables. If the expression contains only one term, it is known as a monomial, while those that contain two or more terms are polynomials.

Labeled algebraic equation illustrating parts of an expression: terms, coefficients, variables, constants, and the full equation, using color-coded annotations for clarity.

There is no limitation to the amount of constant numbers, unknown variables, or operations that can appear in an algebraic expression. In addition, there does not always have to be a variable in the algebraic expression, although it will always have a certain numerical value.

Detailed explanation

Practice Variables and Algebraic Expressions

Test your knowledge with 14 quizzes

\( a+b+bc+9a+10b+3c=\text{?} \)

Examples with solutions for Variables and Algebraic Expressions

Step-by-step solutions included
Exercise #1

3x+4x+7+2=? 3x+4x+7+2=\text{?}

Step-by-Step Solution

Let's simplify the expression 3x+4x+7+2 3x + 4x + 7 + 2 step-by-step:

  • Step 1: Combine Like Terms Involving x x
    The terms 3x 3x and 4x 4x are like terms because both involve the variable x x . To combine them, add their coefficients:
    3x+4x=(3+4)x=7x 3x + 4x = (3 + 4)x = 7x

  • Step 2: Combine Constant Terms
    The expression includes constant terms 7 7 and 2 2 . These can be added together to simplify:
    7+2=9 7 + 2 = 9

  • Step 3: Write the Simplified Expression
    Now, combine the results from Step 1 and Step 2 to form the final simplified expression:
    7x+9 7x + 9

Therefore, the simplified expression is 7x+9 7x + 9 .

Reviewing the choices provided, the correct choice is:

  • Choice 2: 7x+9 7x + 9

This matches our simplified expression, confirming our solution is correct.

Answer:

7x+9 7x+9

Video Solution
Exercise #2

3z+19z4z=? 3z+19z-4z=\text{?}

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Combine like terms by identifying and adding their coefficients.
  • Step 2: Simplify the expression.
  • Step 3: Verify the resulting expression with the provided choices.

Let's work through each step:

Step 1: Identify the coefficients in the expression 3z+19z4z 3z + 19z - 4z . The coefficients are 3 3 , 19 19 , and 4 -4 .

Step 2: Add and subtract these coefficients: 3+194 3 + 19 - 4 .

Step 3: Calculate: 3+19=22 3 + 19 = 22 and then 224=18 22 - 4 = 18 .

Therefore, the simplified expression is 18z 18z .

The solution to the problem is 18z 18z .

Answer:

18z 18z

Video Solution
Exercise #3

11+5x2x+8= 11+5x-2x+8=

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the like terms in the expression.
  • Step 2: Combine the constant terms.
  • Step 3: Combine the coefficients of xx.

Now, let's work through each step:
Step 1: The given expression is 11+5x2x+811 + 5x - 2x + 8. There are constants (11 and 8) and terms with xx (5x and -2x).
Step 2: Combine the constants: 11+8=1911 + 8 = 19.
Step 3: Combine the coefficients of xx: 5x2x=3x5x - 2x = 3x.

After simplification, the expression becomes 19+3x19 + 3x.

The correct solution from the multiple-choice options is 19+3x\boxed{19 + 3x}.

Answer:

19+3X

Video Solution
Exercise #4

5+0+8x5= 5+0+8x-5=

Step-by-Step Solution

To simplify the expression 5+0+8x55 + 0 + 8x - 5, follow these steps:

  • Step 1: Identify and group like terms. In this case, there are constants (5, 0, -5) and a term with a variable (8x).
  • Step 2: Combine the constants: 5+055 + 0 - 5.
  • Step 3: Calculate: 55=05 - 5 = 0.

Now, our expression simplifies to 0+8x0 + 8x, which is simply 8x8x.

Therefore, the simplified expression is 8x8x.

Answer:

8X 8X

Video Solution
Exercise #5

5+89+5x4x= 5+8-9+5x-4x=

Step-by-Step Solution

To solve this problem, we will simplify the expression 5+89+5x4x5+8-9+5x-4x by separately combining the constants and the variable terms.

Step 1: Simplify the constant terms.
5+89=45 + 8 - 9 = 4

Step 2: Simplify the variable terms.
5x4x=x5x - 4x = x

Step 3: Combine the results from steps 1 and 2.
Thus, the simplified expression is 4+x4 + x.

Therefore, the solution to the problem is 4+x4 + x, which corresponds to choice .

Answer:

4+X

Video Solution

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