Mat 8 Merged
Mat 8 Merged
Mat 8 Merged
Date : 01-05-2015
DPP DAILY PRACTICE PROBLEMS
NO.
08
REVISION DPP OF
DEFINITE INTEGRATION & ITS APPLICATION AND INDEFINITE INTEGRATION
505 1007
1. If A =
0
| cos x | dx and B =
505
| sin x | dx, then A + B is equal to
100
2. The least integer greater than x dx
0
is (where {.} is fractional part function)
(A) 50 (B) 51
(C) 52 (D) 53
ex 2 – x2
3. 1– x 1– x 2
dx =
1– x 1 x
(A) ex . +c (B) ex +c
1 x 1– x
ex ex
(C) +c (D) +c
1– x 1 x
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4. Let f(x) = x
2
cos2 x 2x 6 tan x – 2x tan2 x dx and f(x) passes through the point (, 0), then the
3
number of solutions of the equation f(x) = x in [0, 2] is
(A) 1 (B) 2 (C) 3 (D) 4
2
5. Let f(x) is a continuous function symmetric about the lines x = 1 and x = 2. If f(x) dx = 3 and
0
50
x
6
6. x 4 x2 2x 4 3x 2 6 dx is equal to
3/2 3/2
(A)
3x 6
2x 4 6x 2 C (B)
2x 6
3x 4 6x 2 C
18 24
3/2
(C)
2x 6
3x 4 6x 2 C (D) None of these
18
x2
7. For each positive integer n > 1, let Sn represents the area of the region bounded by y 2 1 and
n2
y2
x2 1 , then lim Sn is equal to
n2 n
8x 43 13x38
8. 4
dx =
x13
x5 1
x39 x39
(A) 3
+c (B) 3
+c
3 x13 x 5 1 x13 x5 1
x39 x52
(C) +c (D) +c
5 x13 x 5 1
5
3 x13 x5 1
x x
9. Let
e (f(x) – f '(x))dx = (x), then e f(x)dx is equal to
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10. Suppose f(x) is a real valued differentiable function defined on [1, ) with f(1) = 1. Further let f(x) satisfy
1
f(x) = , then the range of values of f(x) is
x2 f 2 (x)
x
t2
xe
0
dt
11. The value of Lim is equal to
x0 1 x ex
2
f(2t)
12. Let f(x) be a differentiable function such that f(0) = 0 and f '(2t) e
0
dt 5 , then the value of f (4)
equals
(A) 2 n3 (B) n10 (C) n11 (D) 3 n2
x
13. The area enclosed by the curve y 4 – x2 , y 2 sin and the x-axis is divided by y-axis in
2 2
the ratio
2 – 8 2 – 4 –3 2 2
(A) (B) (C) (D)
2 8 2 4 4 2 2 – 8
1 cos2 t
I2 = f x 2 – x dx , then
sin2 t
x 2
x2
15. If g t dt t 2 g t dt , then equation g(x) = has
2
2 x
1 1
(A) 2 solution if | | < (B) 2 solution if | | < & 0
2 2
1 1
(C) 1 solution if = – (D) No solution if | | >
2 2
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[x]
16. If g(x) = {x} , where {.} and [.] represents fractional part and greatest integer function respectively and
k 1
f(k) = g(x)dx (k N), then
k
r 2
(C) –1
r 1
f(r) = n
e
n
1 n(n 1)
(D) f r =
r 0
2
17. If f(x) is a differentiable function such that f(x + y) = f(x) f(y) x, y R, f(0) 0 and
f(x)
g(x)= 2
, then
1 f x
2015 2015
(A)
–2014
g(x)dx
0
g(x)dx
2015
(C)
–2014
g(x)dx 0
2014 2014
(D)
–2014
2g(–x) – g(x) dx 2
0
g(x)dx
2 7
–1 1 –1 sin x
18. Let I =
–1
cot x cot x dx and J =
| sin x | dx , then which of the following is/are correct ?
–2
(A) 2I + J = 6 (B) 2I – J = 3
2 2 2 I 5
(C) 4I + J = 26 (D)
J 2
1
sin n x
2
19. If In =
0 sin
x
dx , where n w, then
2
10 10
(A) In+2 = In (B)
m1
Im 10 (C) I
m1
2m–1 10 (D) In+1 = In
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1
x 4 1 x10065 1
20. If 2015
dx
p
, then
0 1 x 5
(A) Number of ways in which p can be expressed as a product of two relatively prime factors is 8.
(B) Number of ways in which p can be expressed as a product of two relatively prime factors is 4.
(C) Number of ways in which p can be expressed as a product of two factors is 8.
(D) Number of ways in which p can be expressed as a product of two factors is 4.
3n–1 3n
r r
21. If Tn = r
r 2n
2
n 2
and Sn =
r 2n1 r
2
n2
n {1, 2, 3, . . . . }, then
1 1
1 x8 1 x9
22. If I1 = 1 x
0
4
dx and I2 = 1 x
0
3
dx , then
23. Consider a continuous function 'f' where x4 – 4x2 f(x) 2x2 – x3 such that the area bounded by y = f(x),
g(x) = x4 – 4x2, the y-axis and the line x = t (0 t 2) is twice of the area bounded by y = f(x),
y = 2x2 – x3, y-axis and the line x = t (0 t 2) then
(A) f(2) = 0 (B) f(1) = 1/3
(C) f(1) = –2/3 (D) f(x) has two points of extrema
4
24. The value of the definite integral 2
x(3 x)(4 x)(6 x)(10 x) sin x dx equals
a
(sin1 e x sec 1 e x )dx
25. The value of the definite integral
(cot 1
ea tan1 e x )(e x e x )
(a R) is
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(k 1) 4
| sin2x |dx dx
26. Let I =
k
| sin x | | cos x |
, (k N) and J = sin x cos x
0
, then which of the following hold(s)
good ?
/2
sin2x dx
(A) I = 2
0
sin x cos x
(B) I = 4 – 4J
(C) I = 4 – 2J (D) I = 2 – 2J
x8 4
27. If f(x) = x 4
– 2x 2 2
dx and f(0) = 0, then
/2
n 1 x sin2 d, x 0, then
28. If f(x) =
0
2
sin
(A) f(x) = x 1–1 (B) f'(3) =
4
(C) f(x) cannot be determined (D) f'(0) =
2
x
29. If f : R R be a continuous function such that f(x) = 2tf(t)dt , then which of the following does not
1
hold(s) good?
2
(A) f() = e (B) f(1) = e
(C) f(0) = 1 (D) f(2) = 2
3r 2
n 3 b
30. If lim
n
2 f(x)dx , then
n
r 1
n
0
40
(C) S < (D) S > n4
21
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Comprehension # 1 (For Q. No. 32 to 33)
10
cos 4x cos5x cos6x cos7x
Consider the integral I =
0
1 e2 sin 2x
dx
/2
32. If I = k . cos 4x cos5x cos 6x cos7x dx , then 'k' is equal to
0
/4
33. If I = . cos2x cos 4x cos 6x dx , then '' is equal to
0
For i = 0, 1, 2, . . . . , n, let Si denotes the area of region bounded by the curve y = e–2x sin x with x-axis
from x = i to x = (i + 1).
1 e2 1– e –2
(A) (B)
5 5
1 e–2 1 e–
(C) (D)
5 5
S2014
35. The ratio is equal to
S2015
–2 2 –
(A) e (B) e (C) 2e (D) e
36. The value of S
i 0
i is equal to
(A)
e 1 e (B)
e2 e2 1
5e
– 1
5 e 2
–1
e2 1 e2 1
(C) (D)
5 e2 – 1 e2 – 1
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x f(x)
37. Let f(x) be differentiable function satisfying the condition f x, y R – {0} and f(x) 0,
y f(y)
f(1) = 2. If the area enclosed by y f(x) and x2 + y2 2 is A, then find [2A], where [.] represents G.I.F.
2
dx
38. The value of the definite integral (sin x cos x 2
sin x cos x ) sin x cos x
equals
1
39. A continuous real function 'f' satisfies f(2x) = 3 f(x) x R. If f(x)dx 1 , then compute the value of
0
2
definite integral f(x)dx
1
1
1004 1004
x 1– x dx
2010 0
40. If 2 1
= then find the highest prime factor of .
1004
x 1– x
1004 2010
dx
0
ANSWER KEY
DPP # 7
REVISION DPP OF
VECTORS AND T HREE DIMENSIONAL GEOMETRY
1. (C) 2. (C) 3. (B) 4. (B) 5. (A) 6. (A) 7. (A)
8. (C) 9. (A) 10. (C) 11. (B) 12. (C) 13. (C) 14. (B)
15. (C) 16. (B) 17. (A) 18. (A,D) 19. (B,D) 20. (B,D)
21. (B,C,D) 22. (B,C) 23. (B,C) 24. (A,B,C) 25. (A,B,C,D)26. (A,B,D)
27. (A,C,D) 28. (A,C,D) 29. (A,B) 30. (A,C,D) 31. (A,C,D) 32. (A,B,D)
33. (A,C,D) 34. (C,D) 35. (B,D) 36. (A,B,D) 37. (A,D) 38. (D) 39. (C)
40. (B)
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Solution of DPP # 8
TARGET : JEE (ADVANCED) 2015
Course: VIJETA & VIJAY ( ADP & ADR)
MATHEMATICS
505 1007
1. A=
0
| cos x | dx = 505 cos x dx = 1010
0
B=
505
| sin x | = (1007 – 505) | sin x | dx = 1004
0
2 – x2 1 1– x 2 1 1 x
ex . ex dx =
ex dx
3. I=
dx =
1– x 1– x 2 1– x 1– x 2
1– x 1– x 2
1 x 1 x
2 1 x
1 x
= ex. +c
1– x
3
4. f(x) =
2x .cos2 x 6x 2 sin x cos x – 2x 3 sin2 xdx
3 2 3
= 2x .cos 2xdx 3
x sin
= x
2 xdx
.2cos 2x dx sin 2x. x 3 – x3 .2cos 2x dx
f(x) = x3 sin2x +c f(x) = x3 sin2x
5. f(x) = f(2 – x) & f(x) = f(4 – x) f(x) = f(x + 2) f(x) is periodic with period 2
50 2
Now I=
f(x)
0
dx 25 f(x) dx = 75
0
x 2x x
6
6. = x4 x2 4
3 x 2 6 dx = 5
x 3 x 2 x 6 3 x 4 6 x 2 dx
dt t3 / 2
Put 2x6 + 3x4 + 6x2 = t = t. = +c
12 18
7. When n y2 1 & x2 1 –1y1 & –1x1
y
x = –1
y=1
y = –1
x=1
lim Sn = 4
n
f(x) – f(1) tan x – tan 1 –1 –1
f(x) 1 – + tan–1x 1 +
4 4
x x x
2 2
t2
x e t dt
x e t dt
e dt 2
0 0 0 0 0 ex
11. Let = Lim = Lim x
= 2Lim 0 = 2Lim = –2
x 0 (e x 1) 0 x 0 ex x 1 x 0 x x 0 1
x2
x2
2
f(2t)
12. We have f '(2t) e dt 5 Put ef(2t) = y 2f' (2t) ef(2t) dt = dy
0
ef ( 4 ) ef ( 4 )
1
Now e y dy 5 e y dy 10 ef(4) – ef(0) = 10 ef(4) = 10 + e0 = 11
2 f (0 ) f ( 0)
e e
Hence f (4) = n 11
y
x
13. 1 22
2
1 cos2 t
14. I1 =
xf x 2 – x dx
sin2 t
1 cos2 t
= 1 cos
2
2
t sin2 t – x f 1 cos2 t sin2 t – x 2 – 1 cos2 t sin2 t – x [P-5]
sin t
1 cos2 t 1 cos2 t
I1
= 2 f 2 – x x dx –
xf 2 – x x dx I1 = 2I2 – I1 2 I1 = 2I2
I2
=1
sin2 t sin2 t
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x
15. Differentiating both sides g(x) = x – x2 g(x) g(x) =
1 x2
Now, graph of y = g(x) is
y
1/2
–1
x' x
1
–1/2
y'
k 1
k 1 x – k k 1
k 1
16. f(k) = x – k dx f(k) =
k 1 k 1
k k
r 1
Now –1
r 1
f(r) = f(1) – f(2) + f(3) + . . . . . . .
1 1 1 1
= – – + . . . . . . = 1 – n 2
2 3 4 5
0 2 6 7
3 5 sin x sin x
18. I=
–1
2
dx
2
dx
2
0
J=
–2
| sin x |
dx | sin x | dx
6
=0+=
3 1
sin n x – sin n x
2 2 dx
19. In+1 – In =
0
sin
x
2
2cos n 1 x
x
sin
2
In+1 –In
0 sin
x
dx
2
In+1 – In = 0
20. Put x5 = t
1
1 1 t2013
I=
5 1 t
0
2015
dt
1 1
1 1 1 t –2
=
5 1 t 2015
dt
5 2015
dt
0 0 t –1 1
1 1
=
5 2014
p = 5 × 2014 = 2 × 5 × 19 × 53
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x
21. Consider f(x) =
1 x2
y
2/5
3/10
x
0 2 2+h 3–h 3
2+2h
3
x
Area bounded by f(x) with x-axis
x 2
n 2
2
1
Clearly, h[f(2)+ f(2 + h) + . . . . + f(3 – h)] > n 2 > h[f(2 + h) + f(2 + 2h) + . . . . + f(3)]
2 3
y = 2x – x y = f(x)
23. –2
O 4 2
y = x – 4x
t t
0
f(x) – (x 4 – 4x 2 ) dx = 2 2x 2 – x 3 – f(x) dx
0
on differentiating with respect to t.
1 4
f(t) – (t4 – 4t2) = 2(2t2 – t3 – f(t)) f(t) = (t – 2t3)
3
4
24. We have =
2
x(3 x)(4 x)(6 x)(10 x) sin x dx ....(1)
4
Now =
2
(6 x) 3 (6 x) 4 (6 x) 6 (6 x) 10 (6 x) sin(6 x) dx
b b 4
Applying
a
f(x) dx f(a b – x) dx
a
=
(6 x)(x 3)(10 x)x(4 x) sin(6 x) dx ....(2)
2
On adding (1) and (2), we get
4
4
2I = sin x sin(6 x) dx = cos x cos(6 x)
2
2
= – cos 4 + cos 2 + cos 2 – cos 4
(k 1)
| sin 2x |dx
26. We have I =
k
| sin x | | cos x |
; put x = k + t dx = dt
/2 /2
| sin 2x | dx sin2x dx (sin x cos x)2 1
I=
0
| sin x | | cos x |
= 2
0
sin x cos x
= 2
0
sin x cos x
dx
2 2 4
dx dx
= 2 sin x cos x dx 2
0 0
sin x cos x
=4–4 sin x cos x
0
= 4 – 4J
2
x 8 4 4x 4 – 4x 4 x 4
2 – 4x 4 (x 4 2x 2 2)(x 4 – 2x 2 2)
27. f(x) = 4
x – 2x 2 2
dx = 4
x – 2x 2 2
dx = (x 4 – 2x 2 2)
dx
5 3
x 2x
f(x)= + + 2x
5 3
/ 2
n 1 x sin2 d ; / 2
1
28. f(x) =
0
sin2
x0 f(x) =
1 x sin
0
2
d
/2 2
sec dq
f(x) =
1 1 x tan
0
2
put tan = t
dt 1
f(x) = 1 2
f(x) =
1 x
tan –1
1 x t
0 1 x t 0
1
f(x) = . f(x) = . 1 x c put x = 0
2 1 x
+ c = f(0) c = – f(x) = 1 x – 1
x
f '(x)
nf(x) = x2 + nc
29. f(x) =
2t
0
f(t)dt f(x) = 2xf(x)
f(x)
= 2x
2
f(x) = c.e x put x = 1 c.e = f(1) = 0 c=0 f(x) = 0
1
3r 2
n 3
9x
2
30. lim
n
2
n
r 1
n
2 .3dx
0
x
31. tx = y f(y) dy = xn f(x)
0
f(x) = n[f(x) + xf'(x)] f(x)(1 – n) = nx f(x)
f 'x 1 n 1 1– n
. n(f(x)) = nx + nc
f x n x n
1n
n c 2
f(x) = c x as n f(x) = cx–1 = g(x) =
x x
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(32 to 33)
10
cos 4x cos5x cos 6x cos7x
I=
0
1 e 2 sin 2x
dx
10
cos 4x cos5x cos 6x cos7x
I=
0
1 e –2 sin 2x
dx (from p-5)
10
2I = cos 4x cos5x cos 6x cos7x dx
0
2I = 10 cos 4x cos5x cos 6x cos7x dx
0
(from p-7)
/ 2
2I = 20
0
cos 4x cos5x cos 6x cos7x dx (from p-6)
/ 2
I = 10 cos 4x cos5x cos 6x cos7x dx
0
k = 10
Further,
/2
I=5 cos 4x.cos6x. cos12x cos 2x
0
/ 2 / 2
I = 5 cos 4x cos 6x cos12x dx
cos 2x cos 4x cos 6x dx
0 0
/ 4
I = 5 0 2 cos 2x cos 4x cos 6x dx
(from p-6)
0
/4
I = 10 cos 2x cos 4x cos 6x dx
0
= 10
–2x
y=e
y
–2x
y = –e
i1 i1
–2x
e –2x
Now Si =
e sin x dx Si = –2 sin x – cos x
i 5 i
x
–1 1
2 2
x +y =2
1
1 2
A= 2
0
2 – x2 – x2 dx
3 2
2A =
3
+ [2A] = 3
2 2
dx sec 2 x dx
38. Let I =
4 cos x(tan x 1 2 tan x ) tan x cos2 x
I= (1
4
tan x )2 tan x
2t dt 1 1
Put tan x = t2 sec2x dx = 2t dt I= (t 1) ·t 2
I=–2 = – 2 0 2 = 1
1
t 1 1
1
39. We have f(2x) = 3 f(x) ....(1) and f(x)dx 1
0
....(2)
1
1
From (1) and (2),
3
f(2x) dx 1
0
2 2 1 2
1
Put 2x = t,
6
f(t)dt 1
0
0
f(t) dt 6
0
f(t) dt f(t) dt 6
1
2 1
Hence f(t) dt 6 f(t) dt = 6 – 1 = 5
1 0
1
1004
x 1– x
1004 2010
40. Consider I2 = dx Put x1005 = t 1005x1004dx = dt
0
1 1
1 1004 1 1004
1– 1– t 2
1– t
2
So I2 =
1005
0
dt …(i) Also I2 =
1005
0
dt …(ii)
1 1
1 1004 1 1004
I2 =
1005 t 2 – t
0
dt =
1005
t1004 2 – t
0
dx Put t = 2y dt = 2dy
1/ 2 1/ 2
1 1004 1004 1
So I2 =
1005 2y 2 – 2y 2dy =
1005
2.21004.21004 y
1004
1– y 1004 dy
0 0
1/ 2
1 1004
I2 = 22009 y
1004
1– y dy …(iii)
1005
0
1 1/ 2
1004 1004
Now I1 = x1004 1– x dx = 2 x
1004
1– x dx …(iv)
0 0
From (iii) and (iv) we get
1 I I
I2 = 22010 1 22010 1 = 4020
1005 4 I2
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