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# NCERT Solutions for Class 7 Maths Chapter 12 – Algebraic Expressions

NCERT Solutions for Class 7 Maths Chapter 12 is about formulating, combining and finding the values of variables in Algebraic Expressions. In chapter 12 of NCERT Solutions for Class 7 Maths, there are a total of 4 exercises and 25 questions. The Chapter covers the concept of Algebraic Expressions and covers some practical examples where variables are taken and their solutions found.

Class 7 NCERT Solutions for Chapter 12 ‘Algebraic Expressions’ is based on the latest syllabus approved by CBSE. We, at Instasolv, provide the step-by-step solutions of Class 7th Maths Chapter no 12 ‘Algebraic Expressions’. You get Chapter-wise Solutions of NCERT Class 7 Maths Textbook that helps you in understanding the concepts of the Chapter better.

Chapter 12 Algebraic Expressions, of CBSE NCERT Class 7 Maths Book introduces you to basic algebraic concepts that will be applied often in practical use. For the Maths subject in Class 7, we explain the important elements and summarise each part and subpart of the Chapter. The same sequence as in the book will be followed so that it becomes easy to understand and help as a reference. You will be able to strengthen your concepts and score high marks in the exams.

## NCERT Solutions for Class 7 Maths Chapter 12 Algebraic Expressions: Exercise Discussion

The questions of Chapter 12 are based on the topics discussed below. We suggest you follow the NCERT Solutions to get a step-by-step explanation for each answer. These solutions will help you score better in the CBSE Class 7 Maths exam.

Algebraic Expressions – Expressions are the central concept of algebra. This chapter exclusively covers Algebraic Expressions.

How Are Expressions Formed –

A constant has a fixed value while a variable can take any value. Variables are generally denoted by alphabets. Variable and Constants are combined to make Algebraic Expressions by using operations like addition, subtraction, multiplication, and division.

Terms of an Expression –

The individual parts created separately which when added to form an expression are called terms. Terms are added to form an expression so if there is a negative sign then that is considered as part of the term.

A term is a product of its factors. For example, if a term is 3xy then the factors are 3, x,  and y.

The factors are algebraic variables represented by alphabets x and y; and coefficients which are numerical values.

Like and Unlike Terms

Like terms are those which have the same algebraic factors. For example, 3xy and 5xy are like terms.

Unlike terms do not have the same algebraic factors. For example, 2x and 5y are unlike terms.

Monomials, Binomials, Trinomials, and Polynomials

An expression with only one term is called a monomial. For example, 3xy and 2x are monomials.

An expression with two terms is called a binomial. For example, 3xy – 2x is a binomial

An expression with three terms is called a trinomial. For example, x + y + 7 is a trinomial.

In general, an expression with one or more terms is called a polynomial. Monomials, binomials, and trinomials are all a particular type of polynomial.

Addition and Subtraction of Algebraic Expressions

• Adding and Subtracting Like Terms

The sum of two or more like terms is a like term with a numerical coefficient equal to the sum of the numerical coefficients of all the like terms.

The difference of two like terms is a like term with a numerical coefficient equal to the difference between the numerical coefficients of the two like terms.

• Adding and Subtracting Unlike Terms

Unlike terms cannot be added or subtracted like terms. In the case of unlike terms, the two terms are noted together to form a new expression.

• Adding and Subtracting General Algebraic Expressions

The above methods of like and unlike terms together are used to add or subtract general Algebraic Expressions.

Finding the Value of an Expression

The value of an expression depends on the value of the variables that are part of the expression. The methods studied in the various chapters already studied in NCERT Class 7 Maths textbook should be used to find the value of the variables according to the questions.

Using Algebraic Expressions – Formulas and Rules

Perimeter Formulas

– The perimeter of an equilateral triangle is equal to three times the length of its side. If we denote the length of the side of the equilateral triangle by l, then the perimeter of the equilateral triangle is equal to 3l.

– The perimeter of a square is equal to four times the length of the side.   If the length of the side is denoted by l, then the perimeter of the square is equal to 4l.

– The perimeter of a regular pentagon is equal to five times the length of its side. If the length of the side is denoted by l, then the perimeter of the pentagon is equal to 5l.

– This concept can be extended ahead to figures of multiple sides of equal length.

Area Formulas

If we denote the length of a square by l, then the area of the square is l multiplied by l or the square of l.

–  If we denote the length of a rectangle by l and its breadth by b, then the area of the rectangle is l multiplied by b.

– If b stands for the base and h for the height of a triangle, then the area of the triangle is half of the multiple of b and h.

– Use the same concept for parallelograms. You can refer to the material provided by Instasolv chapter-wise of NCERT Solutions for Class 7 Maths.

Rules for Number Patterns

• If a natural number is denoted by n, its successor is (n + 1).
• If a natural number is denoted by n, 2n is an even number and (2n + 1) an odd number.

Some More Number Patterns

Arithmetic series is a kind of number pattern. Every number in the series has the same relation with the numbers adjacent to each. For example, 3, 7, 11, 15 ……n

Every number in the series is the previous number plus four.

Pattern in Geometry

Various patterns can be found in the geometrical shapes we have studied. One such pattern, for example, is, the number of diagonals we can draw from one vertex of a polygon of n sides is n minus three.

### Study Tips for NCERT Class 7 Maths  Chapter 4: Simple Equations

You aim to get a high score in the Class 7 Maths exams. We recommend that you follow Chapter 12 Algebraic Expressions of CBSE NCERT textbook for Class 7 Maths. Our subject matter experts have provided a simple explanation and summary of each part of this Chapter. All of this can be used to develop a better understanding of all the concepts.

If any concept is still not understood, ask the experts on the Instasolv app which does not charge any student for this support.

Do all the exercises, solved examples and self-practice questions on your own before you cross-check from the solutions or ask the experts on the Instasolv app.

Follow the solutions of Algebraic Expressions NCERT Solutions for Class 7 and tips provided by Instasolv and score high marks in your Maths exam.

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