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SAI International School
CLASS-VI
Mathematics
CHAPTER-11: Algebra
Lesson Notes-2
SUBTOPIC:Expressions with variables(Converting expression into
statement, Statement to expression), Use of algebra in practical life
Expressions With Variables
We know that variables can take different values; they have no fixed value. But they are
numbers. That is why as in the case of numbers, operations of addition, subtraction,
multiplication, and division can be performed on them. Using different operations, we
can form expressions with variables like x – 2, x + 1, 3n, 2m, 2y + 5, 3l – 7, etc.
Note: A number of expressions can be immediately evaluated.
For example: 3 × 4 + 6 = 12 + 6 = 18
But an expression containing the variable x cannot be evaluated until x is assigned
same value.
For example,
When x = 1, 4x + 3 = 4 × 1 + 3 = 4 + 3 = 7.
Converting Expression into statement:An expression can be converted into statement in
the following way.
Ex- Expression How formed?
y + 5 5 added to y
t – 7 7 subtracted from t
10 aamultiplied by 10
Converting statement into expression:A statement can be converted into expression.
Ex- Statement Expression
12 subtracted from z z– 12
25 added to r r+ 25
pmultiplied by 16 16 p
Using Expressions Practically:
The use of expressions comes handy in every day.
Ex- if Seema is 5 years older than Ritu and the age of Ritu is given to be z
years. Then Seema’s age is (z + 5) years.
Ex – Sarita has 10 more marbles than Ameena. Let Ameena has x marbles. So
Sarita has (x + 10) marbles.
