Class 7 Maths Chapter 12 Algebraic Expression Exercise 12.3 pdf notes:-

**Exercise 12.3** Class 7 maths Chapter 12 Pdf Notes:-

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## Ncert Solution for Class 7 Maths Chapter 12 Algebraic Expression Exercise 12.3 Tips:

**FINDING THE VALUE OF AN EXPRESSION**

We know that the value of an algebraic expression depends on the values of the variables

forming the expression. There are a number of situations in which we need to find the value

of an expression, such as when we wish to check whether a particular value of a variable

satisfies a given equation or not.

We find values of expressions, also, when we use formulas from geometry and from

everyday mathematics. For example, the area of a square is l

2

, where l is the length of a

side of the square. If l = 5 cm., the area is 52 cm2

or 25 cm2

; if the side is 10 cm, the area

is 102 cm2

or 100 cm2

and so on.

Thus, 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.

Similarly, the difference between two like terms is a like term with a numerical

coefficient equal to the difference between the numerical coefficients of the two

like terms.

Note, unlike terms cannot be added or subtracted the way like terms are added

or subtracted. We have already seen examples of this, when 5 is added to x, we write the

result as (x + 5). Observe that in (x + 5) both the terms 5 and x are retained.

Similarly, if we add the unlike terms 3xy and 7, the sum is 3xy + 7.

If we subtract 7 from 3xy, the result is 3xy ā 7