CBSE Mathematics Class XI

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Mathematics - CBSE CLASS XI

Mathematics

 

EXERCISE 1.2

1. Given function f is defined by f (x) = 5x − 4 . Find the value of x if f (x) = −14 .


2. Given that f (x) = 2x − 3. Find the image of 5.
3. 
   (i) The image of 5.
   (ii) the value of x such that the function f is undefined


4. Given the function h such that
   h(x) = 2x²+3kx+1 and h(1) = 9. Find the value of k.


5. Given the function f : x →3x +1, find
   (a) the image of 2,
   (b) the value of x if f(x) = x.


6. Given the function w : x → 4x + 3, find the value of p such that w(p) = 23 .
7. Given the function n : x → 2x − 5. Find the value of k at which n(k) = k .

1.3 COMPOSITE FUNCTIONS

	The figure shows Set A, B and C. The combined effect of two functions can be represented by the function gf(x) and not fg(x). This is because the range of f has become the domain of function g or f(x) becomes the domain of function g. The concept is: f(x) = 3x f(k) = 3(k) f(3) = 3(3) f[g(x) ]= 3g(x)
Example 1: Given function f : x → x +1and g : x → 3x . Find the composite function gf.
Example 2 : The following information refers to the functions f and g.
Find (a) the value of k, (b) fg(x).

CBSE Mathematics Class XI ( By Mr. Ayaz Khan )
Email Id : [email protected]