# NCERT Solutions for Class 7 Maths Chapter 12 Exercise 12.2

NCERT Solutions for Class 7 Maths Chapter 12 Exercise 12.2 (Ex. 12.2) Algebraic Expression in Hindi and English Medium for CBSE Session 2020-2021. Solutions are available in PDF as well as videos format describing each questions.

Class 7 math exercise 12.2 contains the questions based on addition or subtraction of algebraic expression using like terms. There are only 6 questions given in exercise 12.2 of 7th math and all the question are easy to understand.## Class 7 Maths Chapter 12 Exercise 12.2 Solution

Class: 7 | Mathematics |

Chapter: 12 | Algebraic Expressions |

Exercise: 12.2 | PDF and Videos Solution |

### CBSE NCERT Class 7 Maths Chapter 12 Exercise 12.2 Solution in Hindi and English Medium

### Class 7 Maths Chapter 12 Exercise 12.2 Solution in Videos

#### Factors

Each term of an algebraic expression consists of a product of constants and variables.

A constant factor is called a numerical factor, while a variable factor is known as a literal factor.

#### Coefficient

In a term of an algebraic expression any of the factors with the sign of the term is called the coefficient of the product of the other factors in that term.

Example:

(i) In 5xy, the coefficient of x is 5y and the coefficient of y is 5x.

(ii) In -6ab, the coefficient of a is -6b and the coefficient of b is -6a.

(iii) In -y, the coefficient of y is -1.

#### Constant Term

A term of the expression having no literal factor is called a constant term.

Example:

In the algebraic expression x + 5x – 3, the constant term is -3.

##### Like and Unlike Terms

In a given algebraic expression, the terms having the same literal factors are called like or similar terms, otherwise they are called unlike terms.

##### Addition of Algebraic Expressions

While adding algebraic expressions, we collect the like terms and add them. The sum of several like terms is another like term whose coefficient is the sum of the coefficients of those like terms.

##### Add: 5x² – 7x + 3, – 8x² + 2x – 4 and 7x² – x – 2.

Required sum: = (5x² – 7x + 3) + (-8x² + 2x -5) + (7x² – x – 2)

= 5x² – 8x² + 7x² – 7x + 2x -x + 3 – 5 – 2

= (5 – 8 + 7) x² + (- 7 + 2 -1) x + (3 – 5 – 2)

= 4x² – 6x – 4.

##### Subtraction of Algebraic Expressions

The difference of two like terms is a like term whose coefficient is the difference of the numerical coefficients of the two like terms.

Example: (4x² – 6x²) = (4 – 6) x² = -2x²

##### Rule for Subtraction of Algebraic Expressions

Change the sign of each term of the expression to be subtracted and then add.

##### Subtract (2x² -5x + 7) from (3x² + 4x + 6)

We have: (3x² + 4x – 6) – (2x² – 5x + 7)

= 3x² + 4x – 6 – 2x² + 5x -7

= (3 – 2)x² + (4 + 5)x + (- 6 – 7)

= x² + 9x -13

##### What is the rule for adding and subtracting algebraic terms?

To add two or more monomials that are like terms, add the coefficients; keep the variables and exponents on the variables the same. To subtract two or more monomials that are like terms, subtract the coefficients; keep the variables and exponents on the variables the same.

##### What are the 3 rules of algebra?

There are many laws which govern the order in which you perform operations in arithmetic and in algebra. The three most widely discussed are the Commutative, Associative, and Distributive Laws. Over the years, people have found that when we add or multiply, the order of the numbers will not affect the outcome.

##### Can we add variables with different exponents?

To add or subtract with powers, both the variables and the exponents of the variables must be the same. You perform the required operations on the coefficients, leaving the variable and exponent as they are. These rules are true for multiplying and dividing exponents as well.