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Funções: Tipos, Domínio, Código de Exemplos e Aplicações, Exercícios de Matemática

Este documento aborda os conceitos básicos de funções matemáticas, incluindo seus tipos, domínio, intervalo e alguns exemplos. Além disso, discutimos aplicativas práticas de funções em diferentes contextos.

Tipologia: Exercícios

2013

Compartilhado em 05/01/2013

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FUNCTIONS
[ DOMAIN, RANGE, PERIOD, INVERSE, EVEN or ODD ]
By:- Nishant Gupta
For any help contact:
9953168795, 9268789880
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FUNCTIONS

[ DOMAIN, RANGE, PERIOD, INVERSE, EVEN or ODD ]

By:- Nishant Gupta

For any help contact:

Nishant Gupta, D-122, Prashant vihar, Rohini, Delhi-

1. Definition: Let A & B be two sets. A relation from A to B is called a function if for each a  A there exists

one & only one b  B such that ordered pair (a, b)  f. Denoted f : A  B

A is called Domain B is called Co domain

b is called image of a under f Range : set of images of f

2. Different types of functions

1-1 or injective : If for x 1 , x 2  A ; x 1  x 2  f(x 1 )  f(x 2 )

Onto or surjective : If for all b  B there exists a  A such that f(a) = b

Into : If there is at least one b  B for which there is no a  A such that f(a) = b

Bijective : If a function is both 1-1 & onto then it is known as bijective

IDENTITY FUNCTION : If f (x) = x for x R

EVEN & ODD FUNCTIONS f (-x) =

 f(x) ODD

f(x) EVEN

3. If f : A  B A & B contain n & m elements resp then

Number of 1 – 1 functions from A to B are  

0 if m n

P if m n n

m

Number of onto functions are  

  

 

m

r 1

n r

m r m 1 C r

NOTE : If B contains 2 elements then number of onto functions is 2 n^ – 2

Total number of functions is m n

4. Step function or GREATEST INTEGER FUNCTION [x] :

It means greatest integer x i.e. [2.3] = 2 & [-2.3] = - 3

5. {x} ,Fractional part of x {1.4} = 0.4 {-1.4} = 0.

6. Signum Function :

0 ifx 0

1 ifx 0

1 ifx 0

x

|x|

7. Lograthims:

'log' is involved in many ways so let's be thorough about it

log x is defined for x > 0 only

logA B = x means B = A x

FUNCTIONS

Nishant Gupta, D-122, Prashant vihar, Rohini, Delhi-

  1. In General fog (x)  gof (x) ; but fo(goh) = (fog)oh and (gof)

    = f - og - 
  2. n (A) = 4 & n(B) = 6 then no. of injections

from A to B is

(a) 360 (b) 6^4

(c) 4^6 (d) 120

  1. If n(A) = 5 & n (B) = 2 then no. of surjections

from A to B is

(a) 23 (b) 30

(c) 12 (d) N/T

  1. No. of bijective function. From A to itself when

a contains 106 elements is

(a) 106! (b) (106)^2

(c) 2 106 (d) 2 106

  • 1
  1. Domain of cos x 2 is

(a) R (b) [0, )

(c) {-/2, /2] (d) N/T

  1. Domain of x 1 log ( 1 x)

10

is

(a) [-3, -2] – {- 2.5} (b) [0,1] – {.5}

(c) [-2, 1) – {0} (d) N/T

  1. Domain of log x
    1. 5

(a) (0,1] (b) (0,  )

(c) (.5, ) (d) N/T

  1. Domain of Px 2 6 x 

(a) {2,4} (b) {1,4}

(c) {2, 6} (d) None.

  1. Domain of sin

    x + sec - x 

(a) [ - 1, 1] (b) R – [-1, 1]

(c) {- 1, 1} (d) None.

  1. Domain of   log x x , {. } is fractional part, is

(a) N – {1} (b) R – {1}

(c) R - I (d) N/T

  1. Domain of

1 / 2 2

3 4

x 3 x log 

is

(a) ( -1 , 4 )

(b) ( 1 , 4 )

(c) ( -∞ , -1 )  ( 4 ,∞ )

(d) ( -∞ , 0 )  ( 3 ,∞ )

  1. Domain of f(x) = 3 x 7

183 x 2 x 3

15 x C P 

 

  is

(a) {2, 3} (b) {3,4,}

(c) {2, 3 ,4} (d) {2, 3,4,5}

  1. Domain of log( 2 x x )

2  is

(a) (0, ) (b) (1, )

(c) (0,1) ( 1 ,) (d) N/T

  1. Domain of f(x) = log 2 log 3 log 4 x is

(a) 2 < x < 4 (b) x < 4

(c) x > 4 (d) 5 >x > 4.

  1. Domain of log ( log

 x

x ) , {x} denotes

fractional part , is

(a) R (b) R - I

(c) ( 1 , ∞ ) - I (d) ( -∞ , 1) – I

  1. Domain of (^2 x)x [x]

  is

(a) [ 0 , 2] (b) [0,1]

(c) [ 1, 2] (d) N/T

  1. Domain of Sin

x log 3 is

(a) [-1,9] (b) [1,9]

ASSIGNMENT

FUNCTIONS

Nishant Gupta, D-122, Prashant vihar, Rohini, Delhi-

(c) [-9,1] (d) N/T

  1. If f(x) = x then domain of fof (x) is

(a) (0, ) (b) (-, 0)

(c) {0} (d) N/Ts

  1. Domain of Cos-1 

2 |x| (^) + (log ( - x + 3))-1 (^) is

(a) (-2, 6) (b) [-6, 2]  [2,3]

(c) [-6, 2] (d) N/T

  1. Domain of log|log x| is

(a) (0, ) (b) (1, )

(c) (0,1) ( 1 ,) (d) N/T

  1. Domain of f(x) = 16 x x log x 1 

2

2

1

2    is:

(a) [0, 16] (b) (1,  )

(c) (1, 16) (d) [1, 16]

  1. Domain of f(x) = 3 x 7

183 x 2 x 3

15 x C P 

 

  is

(a) {2, 3} (b) {3,4,}

(c) {2, 3 ,4} (d) {2, 3,4,5}

  1. Range of cos- 1 x

1 x cosec 1 x

1 x 1

(^) is

(a) [- / 2 /2] (b) { / 2}

(c) {0,  / 2} (d) N/T

  1. Range of [Sin x] is

(a) [-1, 1] (b) {-1, 1}

(c) (-1, 1) (d) N/T

  1. Range of [Sin x] , x (-/4, /4) is

(a) [-1, 1] (b) {-1, 1}

(c) (-1, 1) (d) N/T

  1. Range of cos([x] (^) )

(a) 0 (b) {0}

(c) {-1,1} (d) N/T

  1. Range of [Sin x] , x (-/4, /4) is

(a) [-1, 1] (b) {-1, 1}

(c) (-1, 1) (d) N/T

  1. Range of

2

e e

x x  is

(a) R (b) [0,  )

(c) [1,  ) (d) None.

  1. Range of , x 0 1 [x]

e

x

 

(a) ( 0 ,∞ ) (b) [ 0 , ∞ )

(c) ( 1, ∞ ) (d) [1 , ∞ )

  1. Range of f ( x ) = 5 | sinx | - 3|cos x | is

(a) [ 3, -5 ] (b) [ - √34 , √34 ]

(c) [ 5 , √34 ] (d) [ -3 , 5 ]

  1. f : R  R , f (x ) = 2

e e

x x  is

(a) many one onto (b)neither 1-1 nor onto

(c) one-one onto (d) one-one into

  1. If f ( x) = acos ( bx + c) + d then range is

(a) [ d+a , d+2a ] (b) [ a-d , d+a ]

(c) [ d+a , a-d ] (d) [d-a , d+a ]

  1. Range of 1 |x|

x

(a) [-1, 1] (b) R

(c) (-1, 1) (d) N/T

  1. Range of x 5

9 x P (^) 

 is

(a) {5,7} (b) {1,2}

(c) {3,4,…7} (d) N/T

  1. Range of 2 cos 3 x

is

(a) [1/3,1] (b) [1/2,2]

(c) [1/2,1] (d) N/T

  1. Period of tan 4

x cos 3

x  is

(a) 12  (b) 16

(c) 24  (d) N/T

  1. Period of sin  

2 x 3 is

(a) 2  (b) 6 

(c) 6 2 (d) None

  1. Period of sin 2 x + sin 4 x/2 + sin 8 x/4 is

(a) π (b) 4π

(c) 2π (d) 8π.

  1. If f is a periodic functions , then

Nishant Gupta, D-122, Prashant vihar, Rohini, Delhi-

(c) 5 - (1+sin^2 x)^3 (d) N/T

  1. sin
    • 1 (sin12) + cos - (cos12) is equal to

(a) 0 (b) 24-2

(c) 4 -24 (d) N/T

  1. Which of the followings are odd

(a)

e cosx

x

x 

(b) x^2 ln ( x 1 x )

6 3  

(c) g  x g x

x

x

  

(d)g   x g x  h  x h x

  1. If the real -valued function

 1 

n x

x

x a

a fx f is even, then n equals

(a) 2 (b) 2/

(c) 1/4 (d) -1/

upto infinite terms is ( GIF )

(a) 2006 (b) 2007

(c) 2008 (d) 2009

  1. If f ( x ) is polynomial satisfying f ( x ) =

1 f( 1 /x)

f(x) f( 1 /x) f(x)

& f ( 2 ) = 17 then

 

1

1

f(x) dx is equal to

(a) 0 (b) 5/

(c) 12/5 (d) 6/

  1. The fundamental period of f ( x ) = ( sin x )^0 +

( cos x )^0 + ( tan x )^0 is

(a) 2π (b) π

(c) π /2 (d) Does not exist

  1. f : N N where f ( x ) = x + (-1) x^ , then f is

(a) 1-1 into (b) Many one into

(c) 1-1 onto (d) N/T

  1. If f ( x ) = 2

x

e 1

xe

x

x

 

is

(a) Even (b) Odd

(c) Neither (d) Both

  1. If f ( x ) = 

sin x

0

2 tdt then period of f / ( x ) is

(a) π/2 (b) π

(c) 2π (d) 3π/

  1. Period of f ( x ) = [ 8x + 7 ] + | tan 2π x + cot

2πx | - 8x is

(a) 1/2 (b) 1

(c) 1/4 (d) N/T

66. A  B

is a

(a) 1 – 1, on to (b) 1 – 1, into

(c) Many – 1, onto (d) N/T

  1. If log 2 log 3 log 4 x = 1 then x is

(a) 4 9 (b) 3 4

(c) 2^9 (d) N/T

, GIF

(a) 24 (b) 25

(c) 26 (d) N/T

(a) 498 (b) 499

(c) 500 (d) 501

  1. Let f( ) = Sin (Sin +Sin3 ) then f( ) is

(a)  0 if  0 (b)  0 for all

(c)  0 for all  (d) N/T

Nishant Gupta, D-122, Prashant vihar, Rohini, Delhi-

  1. If f (x+2y, x-2y) = x y then f(x , y) is

(a) 8

x y

2 2  (b) 4

x y

2 2 

(c) 8

x y

2 2  (d) N/T

  1. If f (x) = (a -.x n)1/ n, then f [f (x)] is equal to

(a) xn^ (b) a – x

(c) x (d) n x.

  1. f : R  R is f (x) = 2x + sinx, x R

(a) 1 – 1 & on to (b) 1 – 1, into

(c) 1 + 1 into (d) neither 1 1nor into

  1. If f(x) = cos (log x ) then f(x)f(y) -

f(xy) y

x f 2

is

(a) 1 (b) ½

(c) – 2 (d) N/T

  1. f(x) = cos[  2 ]x + cos[-  2 ]x , GIF then

(a) f(/2) = 0 (b) f( ) = -

(c) f(- ) = 0 (d) N/T

  1. If f : [0,1]  B where f (x) = x 2
    • 1, is

surjective then B is

(a) [1,4] (b) [1,2]

(c) [1,∞) (d) N/T

  1. If f (x+1) - f (x-2) = 0 , period f (x) is

(a) 2 (b) 3

(c) 1 (d) Does not exist

  1. Domain of 

 2

1

sin sin x

x x is

(a) (0, ) (b) (-∞, )

(c) [ 2nπ , (2n+1) π ], n  I (d) N/T

  1. Period of 2 | sin2x | - 3 | cos3x | is

(a) π (b) π/

(c) π/2 (d) N/T

  1. Range of y =

x x

e

x

is

(a) [1,e] (b) [1,∞)

(c) ( 0, ∞) (d) N/T

  1. f : R R , defined by f( x) = e x is

(a) 1-1 , onto (b) many 1, into

(c) 1-1, into (d) many 1, onto

  1. |sin x| has inverse if its domain is

(a) [0, π] (b) [0, π/2]

(c) [- π/4, π/4] (d)N/T

  1. If f: RR, g :R  R are functions defined by f

(x) = x + l, g (x) = x^2 - 1 then g { f (3)}will be

(a) 9 (b)

(c) 15 (d) 18

  1. Let f (x ) = x  1

 x

, x  1 then for what value

of α , fof ( x ) is identity function

(a) √2 (b) - √

(c) 1 (d) -

  1. If f ( x ) =

n (^) n ax , x > 0 then on its

domain f( x) is

(a) only injective (b) only surjective

(c) bijective (d) N/T

  1. If f ( x ) = sinx + cosx , g ( x ) = x 2
    • 1 , then g

( f ( x) ) is invertible in domain

(a) [0, π/2 ] (b) [- π/2 , π /2]

(c) [ - π/4 , π /4 ] (d) [ 0, π ]

  1. Number of maps f from set {1, 2,3} into {1, 2,

3, 4, 5} such that f (i) ≤ f (j) whenever i <j is

(a) 60 (b) 50

(c) 30 (d) 35.