NCERT Class 11-Math's: Chapter –2 Relations and Functions Part 2

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Algebra of real functions

(i) Addition of two real functions

Let and be any two real functions, where .

Then we define .

(ii) Subtraction of a real function from another

Let and be any two real functions, where .

Then, we define .

(iii) Multiplication by a Scalar

Let be a real function and α be any scalar belonging to R. Then the product αf is function from X to R defined by .

(iv) Multiplication of two real functions

Let and be any two real functions, where. Then product of these two functions i.e. is defined by

(v) Quotient of two real function

Let f and g be two real functions defined from X → R. The quotient of by denoted by is a function defined from as

Note:

Domain of sum function , difference function and product function .

where

Domain of quotient function

Solved Examples

Short Answer Type

Question 1:

Let and . Determine

(i)

(ii)

(iii)

(iv)

Answer:

Since and . Therefore,

(i)

(ii)

(iii) No, . Since A × B and B × A do not have exactly the same ordered pairs.

(iv)

Hence

Question 2:

Find x and y if:

(i)

(ii)

Answer:

(i)

Since , so

or

and

(ii)

or

Example 3:

If and , , find the set of ordered pairs such that ‘a’ is factor of ‘b’ and .

Answer:

Since

we have to find a set of ordered pairs (a, b) such that a is factor of b and .

Since is a factor of 4 and .

So is one such ordered pair.

Similarly, are other such ordered pairs. Thus the required set of ordered pairs is

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