Chap 6 Algebraic Expressions

Chap 6

Algebraic Expressions

Some Important facts:

1.    The letters, which are used as symbols to represent number, are called literal numbers.

2.    Since literal numbers are used in place of number, therefore, all the rules of fundamental operations (i.e. addition, subtraction, multiplication and division etc.) on numbers are applicable for literal numbers also.

3.    A combination of numbers, literals and arithmetical operations is called an algebraic expression.

4.    The symbols ‘+’ or ‘-‘ separate the expression into several parts each part along with its sign is known as a term of the expression.

5.    According to the number of terms, an expression having only one term is called monomial, that having two terms is called binomial and that having three terms is called trinomial.

6.    The terms, which have same literal factors, are called like terms and the terms which do not have same literal factors are called unlike terms.

7.    The sum of two or more like terms is another like term whose numerical coefficient is the sum of the numerical co-efficient of all the like terms.

8.    The difference of two like terms is another like term whose numerical coefficients is the difference of the numerical coefficients of the two terms.

9.    The quantity, whose numerical value does not change, is called constant.

10. The quantity, whose numerical value goes on changing, is called variable.

11. There are two methods for addition of expression. In first method, expressions are written in column like terms are written in the same column.

In second method, we write the expression in the same horizontal line and connect them by ‘+’ sigs. Then we remove the brackets (if any) and add the like terms. The result so obtained is the required sum.

12. There are two methods for subtraction of expressions, In   first method, we write the expression from which the other is to be subtracted. Write the expression from which the other is to be subtracted. Write the second

expression below the first is such a way that the like  terms lie in column. Change the sign of each term of the second expression, add up each column.

In second Method put ‘-‘sign on the right of the first expression and write all the terms of the second expression in a pair of brackets after this sign. Add the like terms.