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Expressions in Math

Last Updated : 08 Jan, 2025
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Expressions in math are combinations of numbers, variables, operators, and sometimes parentheses that represent a particular value. An expression is a statement involving at least two different numbers or variables and at least one operation, such as addition, subtraction, multiplication, division, exponents, and roots.

An expression in mathematics is a finite combination of constant or variable using operators such as addition (+), subtraction (-), multiplication (×), or division (÷).

Unlike equations, expressions do not contain an equality sign ('='). Some examples of expression include:

  • 2x + 3y
  • 5a − 2b
  • 3/4 ​x + 2
  • 7 + 2 × 5

Expressions in Maths

Some key points regarding expressions are:

  • Expressions do not contain an equality sign ("=")
  • Constants, variables, or products of variables and constants are considered terms
  • When a variable is multiplied by a constant, the constant is referred to as a coefficient

Terms used to Explain Expression

Some common terms used in the explanation of expression are:

  • Variable
  • Constant
  • Coefficients

Variable

A symbol that has variable values or that can be assigned different numerical values is called a variable in an algebraic expression.

Typically, a letter from the English alphabet is used to represent a variable. For instance, x, y, z, i, c or a, b, c, etc.

Constant

A symbol in an algebraic expression with a fixed numerical value is called a constant.

For instance, 7, -5, and 0, 3/5, etc. are all constants.

Coefficients

In mathematics, a coefficients are a multiplicative factor involving a number or a variable in the term of a polynomial, series, or expression.

Coefficients can be either numeric values (constants) or letters standing for constants. For instance, in the term 7x, the coefficient is 7, and in -9y2, the coefficient is -9.

Note: Coefficients can be positive, negative, real, complex, rational, irrational, decimal, or fractional.

How to Write Expression in Math?

To write an expression in math, you need to use a combination of numbers, variables, and operational symbols.

Step 1: Interpret the given text or phrase, identifying key words related to arithmetic operations (e.g., addition, subtraction, multiplication, division)
Step 2: Replace those key words with appropriate mathematical symbols (e.g., +-×÷).

  • and with "+"
  • from with "-"
  • of with "×"
  • by with "÷"

Step 3: Apply the order of operations when necessary, especially when dealing with multiple operations in a single expression.

Step 4: Simply to obtain the final Expression.

For example, to write the expression for "The sum of 7 and the product of -2 and x": 7 + (−2 × x) = 7 - 2x

Types of Expression

Expressions are mathematical statements that combine variables, constants, and operators. There are different types of expressions, including:

  • Numerical Expression
  • Algebraic Expression
  • Radical Expression
  • Fractional Expression

Numerical Expression

A numerical expression is a specific type of mathematical expression that involves numerals (constants) and arithmetic operations.

It produces a result that is either a number or a Boolean value when evaluated. Some examples of numerical expressions include:

  • 5 - 2 + 1/2 (a simple constant expression)
  • 5 + 2 - (3 × (-1) + 7) (this can be simplified to 3)
  • 3 × (8 + 4) - 7 (this can be simplified to 29)

Algebraic Expression

An algebraic Expression is a mathematical expression that consists of variables, constants, and algebraic operations such as addition, subtraction, multiplication, division, and exponentiation.

Some examples of algebraic expression are:

  • 3x - 3xy3 (monomial expression)
  • 5xy + 8 (binomial expressions)
  • ax + by + c (polynomial expressions)

Fractional Expression

A fractional Expression contains fractions within an algebraic expression. For instance, consider the following examples:

  • 3/x + 9/20
  • (x - 2)/(x + 2) + 2
  • 3/(x - 3) - 1/2
  • 4x2/(x - 5)

Radical Expression

A radical expression is a mathematical expression that contains a root symbol, such as a square root, cube root, or fourth root. Examples of radical expression include:

  • 3√(2) - 7
  • √(9x2) + 1/2
  • √(x2 + 2x - 1)

Examples of Expression

There can be various examples of expression involving various functions, constant or variable. Some common examples include:

Polynomial Expression

All the expression of form with any degree is called polynomial expression. Some examples of polynomial expressions include:

  • 2x2 + 3x + 7
  • a2 + 2ab + b2
  • x4 - 2xy2 + 3y4
  • x3 - 8x - 11
  • 3x2 - 5x3 + 8x + 9x2 - 7x + 2x3
  • 2p2 - 7
  • 6m3 - mn + n2 - 4

Trigonometric Expression

Expression containing trigonometric ratios is called trigonometric expression. Examples of trigonometric expression are:

  • sin2x - 2sin x
  • sin x + cos x + tan x
  • sin3x - sin2x + sin x
  • \frac{tan \theta}{\cosec \theta} + \frac{sin \theta}{\cot \theta} + \frac{cos \theta}{\cot \theta}

Logarithmic Expression

A logarithmic expression typically includes a logarithm function, denoted as either logb ​(x), where b represents the base of the logarithm. Some examples are:

  • log10 100 - log10 10 + log10 2
  • ln x + ln y -ln 2
  • logπ ​(π2) - log10 100

Exponential Expression

Exponential expressions involve exponents and are used to represent repeated multiplication. Some examples of exponential expression are:

  • 23 - 32 + 75
  • 103 -102

Factors of Expression

A factors of an expression is a number or expression that divides the expression evenly.

For example, in the expression 2x + 4, both 2 and x + 2 are factors of the expression. Some more examples of factors of expression are:

  • For 3ab + 6c, factors are 3 and ab + 2c.
  • For x2 - 5x + 6, (x - 2) and(x - 3) are the factors.
  • For 2ab - 6ab2, 2b and a + 3ab are the factors.

Equation vs Expressions in Math

Expressions-in-Maths

Key difference in equations and expression in math is given below:

FeatureEquationExpression
StructureTwo expressions connected by an "equal to" (=) sign.Combination of numbers, variables, and operation symbols.
Number of expressionsTwoOne
PurposeRepresents an equality between two mathematical statements.Represents a value or a calculation without requiring equality.
SolutionOften solved to find a specific value for a variable.Can be simplified to obtain a final value.
Example2x + 5 = 113x2 - 2y
Real-world useBalancing chemical equations, finding distances, calculating speed, etc.Representing areas, sums, volumes, etc.

Solved Examples on Expressions

Example 1: Find the coefficient of term 7y in the expression 6x2+ 7y + 3.
Solution:

Coefficient of term 7y in the expression 6x2+7y +3 is "7".

Example 2: Find the terms in the expression 5x +6y +3.
Solution:

No. of terms in the expression is 5x , 6y, 3.

Example 3: Find the factors in the expression 7x3+ 5x2+ 6x + 2.
Solution:

Factors in the expression are 7, x3, 5, x2, 6, x, 2.

Example 4: What type of algebraic expression is 4x + 5?
Solution:

4x + 5 has two monomials 4x and 5 and hence it is a binomial. Now, since every binomial is a type of polynomial.
Therefore, 4x + 5 is a binomial.

Example 5: Identify the terms and coefficients in the expression 3a2 +2ab.
Solution:

There are two terms in the expression 3a2, 2ab.

Coefficients in the expression are 3, 2.


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