Method of Differentiation WA

May 31, 2018 | Author: Amanjot Kaur | Category: N/A
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BANSALCLASSES TARGET IIT JEE 2007 

M A T H E M A T I C S NUCLEUS

QUESTION BANK ON 

METHOD OF DIFFERENTIATION

Time Limit : 3 Sitting Each of 70 Minutes duration approx.

Question bank on Method of differentiation There are 72 questions in this question bank.  Select the correct alternative : (Only one is correct)

Q.1

If g is the the inve invers rsee of f & f  (x) = (A) 1 + [g(x)]5

Q.2

If y = tan1

(B)

1 x 5

  then g  (x) =

1 1  [g (x )]

(B) 1

1

2

 3x  4  1 (B)  2 tan  .   5x  6  (5x  6) 2

3

 If y = sin1    x 1  x 

(D) none 1  x 2  &

x

dy dx

(B) sin1 x

=

1 2 x (1  x )

+ p, then p =

(C) sin1 x

(D) none of these

dy  2x  1 & f  (x) = sin s in x then =   dx  x 2  1 

If y = f 

(A)

(C)

1 x

1  x  2

1 x

 2x  1  sin  2   x  1 

 x2 2

 x2

1  x  2

 

(B)

 2x  1   x 2  1 

 sin 

2

5

 

210

(B)

y x

 Bansal C lasses

 

(B)

2

2

2

(D) none

1   a 2 a 10

If sin sin (xy (xy) + cos cos (xy) (xy) = 0 then then (A)

  x   sin   2x  1  x  1  1  x 

2 1 x

2

Let Let g is the invers inversee funct function ion of f & f  (x) =

(A)

Q.7

(D)

dy  3x  4  & f  (x) = tan x2  then  = dx  5x  6 

(A) 0

Q.6

(D) none

1  [g (x )]5

(C ) 0

 3 tan x 2  4     tanx2 (C) f  2  5 tan x  6 

Q.5

1

If y = f 

(A) tanx

Q.4



(C)

5

  n xe2   d 2y 1 3  2 n x     n ex 2   + tan 1  6 n x  then dx2 =

(A) 2

Q.3

1



dy dx y x

x10

1  x  2

. If g(2) = a then g  (2) is equal to

a

10

(C)

1  a

(C)



2

 

(D)

 

(D)

1   a 10 a2

=  

x y

Q. B. on Method of differentiation

x y

[2]  

Q.8 Q.8

If y = sin sin1

 2 then

1 x

2

(A)

Q.9

2x

 

5

dy 

dx  x   2

 is :

2

(B)

(C)

5

2



(D) none

5

1   1     w.r.t. 1   x 2 at x = is : 2 2  2x  1 

The The deri deriva vati tive ve of sec1  (A) 4

(B) 1/4

(C ) 1

(D) none

  d    3 d2 y  Q.10 Q.10 If y  = P(x), is a polynomial of degree 3, then 2    y . 2  equals :  dx    dx   2

(A) P  (x) + P  (x)

(B) P  (x) . P  (x)

(C) P (x) (x) . P  (x) (x)

(D) a const onstan antt

Q.11

Let f(x) be be a quadratic expression which is positive for all real real x . If  g(x) = f(x) + f  (x) + f  (x), then for any real x, which one is correct . (A) g(x) < 0 (B) g(x) > 0 (C) g(x) = 0 (D) g(x)  0

Q.12 Q.12

If x p . yq = (x + y) p + q   then

dy dx

is :

(A) independe independent nt of p but depend dependent ent on q (C) dependent ent on both p & q

Q.13 Q.13

(B) dependen dependentt on p but indepe independe ndent nt of q (D) independent of p & q both .

g (x) . cos cos  1x if x  0 where g(x) is an even function differentiable at x = 0, passing 0 if x 0  

Let Let f(x) f(x) = 

through the origin . Then f  (0) : (A) is equal to 1 (B) is equal to 0

Q.14 Q.14

If y =

1 1  x n  m

 xp m

(A) emnp Q.15

log

sin

cos 2x 2

 xp n

1 1  x m  p

x

n  p   then

n p

dy

 at e m  is equal to:

dx

(C) enp/m

(D) none

(C ) 4

(D) none of these

x has the value equal to 2

(B) 2

If f is differenti differentiable able in (0, 6) & f  (4) = 5 then Limit x   2 (A) 5

Q.17 Q.17

1  x m  n

+

(B) emn/p

(A) 1 Q.16

1

(D) does not exist

log sin 2 x cos x

Lim x 0

+

(C) is equal to 2

(B) 5/4

 f cx 2 h  = 2x

f (4 )

(C) 10

(D) 20

Let l  =  = xLim xm (l   (l n x)n where m, n  N then : 0 (A) l i l  is independent of m and n (B) l  is  is independent of m and depends on m (C) l  is  is independen independentt of n and and depend dependent ent on on m (D) l  is  is dependent on both m and n

 Bansal C lasses

Q. B. on Method of differentiation

[3]  

cos x

Q.18 Q.18

x

Let Let f(x f(x)) = 2 sin x x 2 tan x

x

(A) 2

sin x

2

(C )

cos x

sin 3x

(A) 0

3 cos 3x

(C ) 4

f 2 (x  h)  f 2 (x) h

 where f  (x) means [f(x)]2. If f(x) = x l nx nx then

 

(B)

f (x ) 

3

g (x )

x   2

(C ) 0

2

 is equal to : (D) none

h



(B) 5f  (x) x

If y = x + e   then x

(A) e

d 2x dy 2



ex

1 e  x

3

If x y + y  = 2 then the value of



3 4

 

(C ) 0

(D) none

is :

(B)

2

(A) Q.25 Q.25

(D) none

f (x  3h)  f (x  2 h) If f(x) is a different differentiable iable function function of x then Limit  = h 0

(A) f  (x)

Q.24 Q.24

(C) 4e

If f(4) = g(4) g(4) = 2 ; f  (4) = 9 ; g  (4) = 6 then Limit x   4 (A) 3 2

Q.23 Q.23

(D) 12

People living living at Mars, Mars, instead of the usual usual definition definition of derivative derivative D f(x), define define a new kind of derivative, D*f(x) by the formula

D * f (x )  has the value x e (A) e (B) 2e

Q.22

(D) 1

    2 

(B) – 12

D*f(x) = Limit h 0

Q.21

1

Let Let f(x) f(x) = cos 2x sin 2x 2 cos 2x   then f    = cos 3x

Q.20 Q.2 0

f  (x)  = 2x  . Then Limit x   0 x 1

(B) cos x

Q.19 Q.19

1

(B)



3 8

d 2y dx 2

(C)

3



ex

1 e  x

2

5

 Bansal C lasses

(B) 1/5

1



1 e

x



3

at the point point (1, 1) is :  

(C)



5 12

If f(a) f(a) = 2, f  (a) = 1, g(a) =  1, g  (a) = 2 then the value of Limit xa (A)

(D)

(C ) 5

Q. B. on Method of differentiation

(D) none

 g (a ) . f (x) is: xa

g (x) . f (a )

(D) none

[4]  

Q.26

If f is twice twice differen differentiabl tiablee such that f  (x)   f (x) , f  (x)  g(x) h  (x)   f (x)

2

2

  g(x) and h (0)  2 , h (1)  4

then the equation y = h(x) represents : (A) a curve of degree 2 (C) (C) a stra straig ight ht line line with ith slo slope 2

Q.27

(B) a curve passing through the origin (D) (D) a stra straig ight ht line line with with y inte interc rcep eptt equ equal to  2.

R T

The derivati derivative ve of the functio function, n, f(x)=co f(x)=coss-1 S w.r.t. 1   x 2 at x = (A)

3

3 4

 

2

1 13

U W

R T

 3 sin x) V  + sin1 S

(2 cos x

1 13

U W

 3 sin x) V

is : (B)

5

 

2

10

(C)

(D) 0

3

Q.28

Let f(x) be a polynomial in x . Then the second derivative of f(e x), is : (A) f  (ex) . ex + f  (ex) (B) f  (e   x) . e2x + f  (ex) . e2x (C) f  (ex) e 2x (D) f  (ex) . e2x + f  (ex) . ex

Q.29

The solutio solution n set of f  (x) > g  (x), where f(x) = (A) x > 1

(2 cos x

(B) 0 < x < 1

1

(52x + 1 ) & g(x) = 5x + 4x (l  (l n 5) is :

2

(C ) x

0

(D) x > 0

dy 1 x2  1 1  + sec , x > 1 then is equal equal to :   dx x 1 x2  1 2

Q.30 Q.30

x If y = sin sin1 2

(A)

Q.31 Q.31

Q.33

x4

If y = (A)

Q.32

x

 

1 x

x

x

(B)

x

x

x2

x

a   b  a   b  a   b  a

ab

  2 ay

(B)

(C ) 0

1

x4

  ......   then

 b ab

  2 by

 

dy dx

(C)

(D) 1

 = a ab

  2 by

 

(D)

 b ab

  2 ay

Let f (x) be a polynomial polynomial function function of second second degree. degree. If f (1) = f (–1) and a, b, c are in A.P., A.P., then f '(a), f '(b) and f '(c) are in (A) G.P. (B) H.P. (C) A.G.P. (D) A.P. y

y1

y2

If y = sin mx then the value of y 3

y4

y6

y7

y 5 (where subscripts subscripts of y shows s hows the order of of derivatiive) is: y8

(A) independent independent of x but dependent dependent on m (C) dependent on both m & x

 Bansal C lasses

(B) dependent dependent of x but independent independent of m (D) independ endent of m & x .

Q. B. on Method of differentiation

[5]  

Q.34 Q.34

If x2 + y2 = R 2  (R > 0) then k =

y 

1  y  2

1

(A) – Q.35

Q.36 Q.36

1

(B) –

2



3

 where k in terms of R alone is equal to

(C)



2

(D) –



2 2



If f & g are differentia differentiable ble functions functions such that g  (a) = 2 & g(a) = b and if fog is an identity function then f  (b) has the value equal to : (A) 2/3 (B) 1 (C ) 0 (D) 1/2 Give Given n f(x) f(x) = 

x3 3

 + x2 sin 1.5 a  x sin a . sin 2a  5 arc sin (a2  8a + 17) then : (B) f  (sin8) (sin 8) > 0 (D) f  (sin (sin 8) < 0

(A) f(x) is not defined at x = sin 8 (C) f  (x) is not defined at x = sin 8 Q.37 Q.3 7

A function f, defined for all positive real numbers, satisfies the equation f(x2) = x3 for every x > 0 . Then the value value of f  (4) = (A) 12 (B) 3 (C) 3/2 (D) cannot be determined

Q.38

Given Given : f(x) = 4x3  6x2 cos 2a + 3x sin 2a . sin 6a +

2

If y = (A + Bx) e

d y  + (m  1)2 ex  then

mx

x

dx

mx

(A) e

(B) e

2 a  a  2

then :

(B) f  (1/2) < 0 (D) f  (1/2) > 0

(A) f(x) is not defined at x = 1/2 (C) f  (x) is not defined at x = 1/2

Q.39

n

2

 2m

dy dx

+ m2y is equal to :

(C) emx

(D) e(1  m) x

Q.40 Q.40

Supp Suppos osee f   (x) = eax + e bx, where a  b, and that  f   '' (x) – 2 f   2 f   ' (x) – 15 f   15 f   (x) = 0 for all x. Then the product ab is equal equal to (A) 25 (B) 9 (C) – 15 (D) – 9

Q.41

Let h (x) be differentiabl differentiablee for all x and let f   let f   (x) = (kx + ex) h(x) where k is some constant. If h (0) = 5, h ' (0) = – 2 and f ' (0) = 18 then the value of k is equal to (A) 5 (B) 4 (C ) 3 (D) 2.2

Q.42 Q.42

Let ef(x) = l n x . If If g(x) is the inverse function of f(x) then g  (x) equals to : (A) ex

Q.43

(B) ex + x

(C ) e ( x 

ex )

(D) e(x + l n x)

The equatio equation n y2exy = 9e –3·x2 defines y as a differentiable function of x. The value of

dy dx

for 

x = – 1 and y = 3 is (A) –

15 2

 Bansal C lasses

(B) –

9 5

(C ) 3

Q. B. on Method of differentiation

(D) 15

[6]  

Q.44 Q.44

 

x Let Let f(x f(x)) = x

x

 and g(x) = x

 xx    then :

(A) f  (1) = 1 and g  (1) = 2 (C) f  (1) = 1 and g  (1) = 0 Q.45

The functi function on f(x) f(x) = ex + x, being differentiable and one to one, has a differentiable inverse f  –1(x). The value of (A)

Q.46 Q.46

(B) f  (1) = 2 and g  (1) = 1 (D) f  (1) = 1 and g  (1) = 1

d dx

 –1  (f  ) at the point f( l n2) is

1

 

n 2

(B)

1 3

log sin|x| cos3 x

If  f  (x)  f  (x) =

log sin|3x| cos

3

 

 x     2 

=4

for |x| <

(C)

 3

for x = 0

(A) 0

If y =

(B)

If y is a function function of x then

(A)

d y2

+x

(C ) 2

dx dy

 (a  b ) 2 (a  x) (x  b ) 2x

d2 y d x2

+y

dy dx

(D) 4

 (C)



(a  b ) 2 (a  x) (x  b )

  (D)

 (a  b ) 2 (a  x) (x  b ) 2x

= 0 . If x is a function of y then the the equation equation becomes : 3

 d x  (B)   = 0 2 +y   d y  dy d2 x

=0 2

 d x  (C)  =0 2  y   d y  dy d2 x

is

dy  (b  x) x  b   then  wherever it is defined is equal to : dx a x  x b

 (a  b) (a  x) (x  b)

d2 x

      ,    3 3 

a x

x

(A)

Q.48

(B) 3 (a  x)

(D) none

4

x  0

then, the number of points of discontinuity of f in

Q.47 Q.47

1

2

 d x  (D)   = 0 2  x   d y  dy d2 x

Q.49

A functi function on f (x) satisfie satisfiess the condit condition ion,, f (x) = f  (x) + f  (x) + f  (x) + ......  where f (x) is a differentiable differentiable function function indefinitely indefinitely and dash dash denotes denotes the order of of derivative derivative . If If f (0) = 1, then f (x) is : x/2 x 2x (A) e (B) e (C) e (D) e4x

Q.50 Q.50

If y =

cos 6x  6 cos 4 x  15 cos 2 x  10

cos 5x  5 cos 3x  10 cos x (A) 2 sinx + cosx (B) –2sinx

 Bansal C lasses

, then

dy

dx (C) cos2x

=

Q. B. on Method of differentiation

(D) sin2x

[7]  

Q.51 Q.51

If

d 2 x  dy 



3

 +

dy 2  dx 

d 2y dx 2

(A) 1

Q.52 Q.52

= K then the value of K is equal to (B) –1

(C ) 2



(D) 0

  



1

1  1 x  sin 1 2 x (1 x)  where x   0 ,  If f(x) f(x) = 2 sin  

2

then f ' (x) has the value equal to 2

(A)

(B) zero

x (1  x)



Q .5 3

 e y = f(x) =    0

Let

2

(C) 

x (1 x)

 

(D) 

1 x2

x

 0

if x

 0

if

Then which of of the following can best best represent the graph of of y = f(x) ?

(A)

Q.54

(B)

Diffrenti Diffrential al coefficien coefficientt of (A) 1

Q.55

1

 m  n   m n  

  

  .  x n   

     

m n

(B) 0



(D)

1 

b x  hg

(B) (B) 2 f(h) f(h) + hf '(h) '(h)

x

  m n   

 m

2

(B) (B) 24 a (ax (ax + b)2

w.r.t. w.r.t. x is

h

d 3y dx 3

x mn

 2h f (h )

(C) (C) hf( hf(h) h) + 2f '(h '(h)

If y = at + 2bt + c and t = ax  + 2bx + c, then (A) 24 a2 (at (at + b)



1

(D)

f (x )



2

  . x   

m

n 

(C ) – 1

Let f (x) (x) be diffrentiable diffrentiable at x = h then Lim x h (A) (A) f(h f(h)) + 2hf 2hf '(h) '(h)

Q.56 Q.56

  x   

(C)

is equal to (D) (D) hf( hf(h) h) – 2f '(h '(h)

  equals

(C) 24 a (at + b) 2

(D) 24 a 2 (ax + b)

1   x x    has the value equal  a a rc t a n  b arc t a n Q.57   xLimit equal to  0 x x  a  b    

(A)

ab 3

 Bansal C lasses

(B) 0

(C)

(a 2

 b2 )

6a 2 b 2

Q. B. on Method of differentiation

(D)

a2

 b2

3a 2 b2

[8]  

Q.58

 x     f  ( x )   f  ( y) for all x, y &  y 

Let f (x) be defined for all x > 0 & be continuous. continuous. Let f(x) satisfy  f   f(e) = 1. Then :

Q.59

Q.60 Q.60

(A) f(x) is bounded

 1  (B) f     0 as x  0  x 

(C) x.f(x)1 as x 0

(D) f(x) = l n x

Suppose Suppose the function function  f   (x) – f   – f   (2x) has the derivative 5 at x = 1 and derivative 7 at x = 2. The derivative of the function f   function f   (x) – f   – f   (4x) at x = 1, has the value equal to (A) 19 (B) 9 (C) 17 (D) 14

If y =

x4  x2 1 x

(A) cot

Q.61

2

 3x  1

5

 and

dy dx

 = ax + b then the value of a + b is equal to

(B) cot

8

5

(C) tan

12

5

(D) tan

12

5 8

Suppos Supposee that that h   (x) =  f    (x)· g   g (x) (x) and F(x) =  f   g ( x)  , where  f    (2) = 3 ;  g (2) (2) = 5 ;  g '(2) '(2) = 4 ; f '(2) = –2 and f '(5) = 11, then (A) (A) F'(2 F'(2)) = 11 h'(2 h'(2)) (B) (B) F'(2 F'(2)) = 22h' 22h'(2 (2))

(C) (C) F'(2 F'(2)) = 44 h'(2 h'(2))

(D) (D) none one

Q.62 Q.62

Let  f   (x) = x3 + 8x + 3 which one of the properties of the derivative enables you to conclude that f   that f   (x) has an inverse? (A) f   (A) f  ' (x) is a poly polyno nomi mial al of even even degr degree ee.. (B) (B) f   ' (x) is self inverse. (C) domain of  f   ' (x) is the range of  f  ' (x). (D) f   ' (x) is always positive.

Q.63

Which one of the following statements is NOT CORRECT ? (A) The derivative of a diffrentiable periodic function is a periodic function with the same period. (B) If f (x) and g (x) both are defined defined on the entire number number line and and are aperiodic aperiodic then the function F(x) = f (x) . g (x) can not be periodic. periodic. (C) Derivative of an even differentiable function is an odd function and derivative of an odd differentiable function is an even function. (D) Every function f (x) can be represented as the t he sum of an even and an odd function

 Select the correct correct alternatives : (More than one are correct) correct)

Q.64

If y = tanx tan x tan tan 2x tan3x then

dy dx

 has the value equal to :

(A) 3 sec2 3x tan x tan 2x + sec2 x tan 2x tan 3x + 2 sec2 2x tan3x tanx (B) 2y 2y (cosec (cosec 2x + 2 cosec cosec 4x + 3 cosec cosec 6x) 2 2 2 (C) 3 sec 3x  2 sec 2x  sec x (D) sec2 x + 2 sec 2 2x + 3 sec 2 3x Q.65 Q.65

x

If y = e

(A)

e

x

 e

 e 2 x

 Bansal C lasses

x

 then

dy dx

x

(B)

 equals e x

 e 2x

x

(C)

1 2 x

y2  4  

Q. B. on Method of differentiation

(D)

1 2 x

y2  4

[9]  

Q.66 Q.66

dy

2

If y = xx  then (A) 2 l n x . xx

2

(B) (2 l n x + 1). 1). xx

(C) (2 l n x + 1).x Q.67 Q.67

Let y = (A)

Q.68 Q.68

1

 

2 y  1



2y

(B)

 

2x

dy dx

(B)

dy dx

=

x x   2 y

1  4x

(D)

y 2x

y

has the value equal to : 1 1 2

 2

  1

2x 1  2 y

(C) 1  2y

x

 dv

 du

 u

dx

d 2v

dx

2

2

 = u  + v

(B)

= 2u

dx 2

(D)

2y

x

x

Let f (x) (x) =

d2 u dx2

=2v

(D) none of these

 2 x 1 . x then then : x 1 1

(A) f  (10) = 1 (C) domain of f (x) is x  1

(B) f  (3/2)   =  1 (D) none

Two functions functions f & g have have first & second derivatives at x = 0 & satisfy the relations, relations, f(0) =

2 g(0)

 , f  (0) (0) = 2 g  (0) = 4g (0) , g  (0) = 5 f  (0) = 6 f(0) = 3 then :

(A) if h(x) =

f (x ) g(x)

 then h  (0) =

15

(B) if k(x) = f(x) . g(x) sin x then k  (0) = 2

4

1 g  (x ) (C) Limit  = x   0 f  (x)

Q.72 Q.72

1

(C)

The The funct function ionss u = e x sinx ; v = ex cos x satisfy the equation equation :

(C)

Q.71

2

2 (D) x x  1 . l n ex2

 x  x  ......   then

1

(A) v

Q.70 Q.70

x2

If 2x + 2y = 2x + y  then

(A) Q.69

x

=

dx

If y = x ( (A) (C)

y x

n x )

n ( n x )

 n x y

x n x

  , then n x

  1

(D) none

2

dy dx

  is equal to :

 2 n x n n x 

((l n x)2 + 2 l n (l  (l n x))

 Bansal C lasses

(B)  

(D)

y

( l n x)  (l   (l n x) l n (l   (2 l n (l  ( l n x) + 1)

x y n y x n x

 (2 l n (l  (l n x) + 1)

Q. B. on Method of differentiation

[10]  

 ANSWER KEY      D   ,    B    2    7   .    Q

    C   ,    B   ,     A    1    7   .    Q

    B   ,      A    0    7   .    Q

    C   ,    B   ,     A    9    6   .    Q

  ,    C   ,    B   ,     A    8    6   .    Q     D

    D   ,    C   ,     A    7    6   .    Q

    D   ,    C    6    6   .    Q

    C   ,     A    5    6   .    Q

    C   ,    B   ,     A    4    6   .    Q

    B    3    6   .    Q

    D    2    6   .    Q

    B    1    6   .    Q

    B    0    6   .    Q

     A    9    5   .    Q

    D    8    5   .    Q

    D    7    5   .    Q

    D    6    5   .    Q

     A    5    5   .    Q

    B    4    5   .    Q

    C    3    5   .    Q

    B    2    5   .    Q

    D    1    5   .    Q

   5   .    Q     B    0

   4   .    Q      A    9

   4   .    Q     C    8

    B    7    4   .    Q

   4   .    Q     C    6

   4   .    Q     B    5

   4   .    Q     D    4

   4   .    Q     D    3

   4   .    Q     C    2

   4   .    Q     C    1

    C    0    4   .    Q

     A    9    3   .    Q

    D    8    3   .    Q

    B    7    3   .    Q

    D    6    3   .    Q

    D    5    3   .    Q

    B    4    3   .    Q

    D    3    3   .    Q

    D    2    3   .    Q

    D    1    3   .    Q

    C    0    3   .    Q

    D    9    2   .    Q

    D    8    2   .    Q

    C    7    2   .    Q

    C    6    2   .    Q

   2   .    Q     C    5

   2   .    Q     B    4

   2   .    Q     B    3

   2   .    Q     B    2

   2   .    Q      A    1

  .    Q     C    0    2

    C    9    1   .    Q

   1   .    Q     B    8

  .    Q      A    7    1

  .    Q     D    6    1

    C    5    1   .    Q

    D    4    1   .    Q

    B    3    1   .    Q

    D    2    1   .    Q

    B    1    1   .    Q

    C    0    1   .    Q

     A    9   .    Q

    C    8   .    Q

    B    7   .    Q

    B    6   .    Q

    B    5   .    Q

  .    Q     D    4

  .    Q     B    3

    C    2   .    Q

     A    1   .    Q

 Bansal C lasses

Q. B. on Method of differentiation

[11]  

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