# Class 7 Maths Chapter 12 Algebraic Expressions

NCERT SOLUTIONS FOR CLASS 7 MATHEMATICS

ALGEBRAIC EXPRESSIONS – Lesson 12

Summary:

*Algebraic expressions are formed from variables and constants.

*We use the operations of addition, subtraction, multiplication and division on the variables and constants to form expressions.

* A term is a product of factors. Factors containing variables are said to be algebraic factors.

* The coefficient is the numerical factor in the term.

* Any expression with one or more terms is called a polynomial.

* A one term expression is called a monomial.

* A two term expression is called a binomial.

* A three term expression is called a trinomial.

* Terms which have the same algebraic factors are like terms.

* Terms which have different algebraic factors are unlike terms.

* The sum (or difference) of two like terms is a like term with coefficient equal to the sum (or difference) of the coefficients of the two like terms.

* When we add two algebraic expressions, the like terms are added as given above: the unlike terms are left as they are.

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Exercise 12.1

1. Get the algebraic expressions in the following cases using variables, constants and arithmetic operations.

i) Subtraction of z from y.

ii) One – half of the sum of numbers x and y.

iii) The number z multiplied by itself.

iv) One – fourth of the product of numbers p and q.

v) Numbers x and y both squared and added.

vi) Number 5 added to three times the product of numbers m and n.

vii)Product of numbers y and z subtracted from 10.

viii) Sum of numbers a and b subtracted from their product.