NCERT Book Class 6 Maths Chapter 11 Algebra

Algebra

Chapter 11
11.1 Introduction

Our study so far has been with numbers and shapes. We have learnt numbers,
operations on numbers and properties of numbers. We applied our knowledge
of numbers to various problems in our life. The branch of mathematics in
which we studied numbers is arithmetic. We have also learnt about figures in
two and three dimensions and their properties. The branch of mathematics in
which we studied shapes is geometry. Now we begin the study of another
branch of mathematics. It is called algebra.
The main feature of the new branch which we are going to study is the use
of letters. Use of letters will allow us to write rules and formulas in a general
way. By using letters, we can talk about any number and not just a particular
number. Secondly, letters may stand for unknown quantities. By learning
methods of determining unknowns, we develop powerful tools for solving
puzzles and many problems from daily life. Thirdly, since letters stand for
numbers, operations can be performed on them as on numbers. This leads to
the study of algebraic expressions and their properties.
You will find algebra interesting and useful. It is very useful in solving
problems. Let us begin our study with simple examples.

11.2 Matchstick Patterns
Ameena and Sarita are making patterns with matchsticks. They decide to make
simple patterns of the letters of the English alphabet. Ameena takes two
matchsticks and forms the letter L as shown in Fig 11.1 (a).