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12th Grade > Mathematics

INDEFINITE INTEGRATION MCQs

Total Questions : 30 | Page 1 of 3 pages
Question 1. If dxx1x3=aln(1x3+b1x3+1)+k, then
  1.    b=1,a=1
  2.    b=1,a=−13
  3.    b=1,a=−23
  4.    None of these
 Discuss Question
Answer: Option B. -> b=1,a=−13
:
B
I=dxx1x3Put1x3=t23x2dx=2tdtI=23dt(1t2)=13(11t+11+t)dt.=13log1+t1t+c=13log1+1x311x3+c.
Question 2. Let x2nπ1,nϵN. Then, the value of x2sin(x2+1)sin2(x2+1)2sin(x2+1)+sin2(x2+1)dx is equal to
  1.    log|12sec(x2+1)|+C
  2.    log|sec(x2+12)|+C
  3.    12log|sec(x2+1)|+C
  4.    None of these
 Discuss Question
Answer: Option B. -> log|sec(x2+12)|+C
:
B
We have, x2sin(x2+1)sin2(x2+1)2sin(x2+1)+sin2(x2+1)dx=x2sin(x2+1)2sin(x2+1)cos(x2+1)2sin(x2+1)+2sin(x2+1)cos(x2+1)dx=x1cos(x2+1)1+cos(x2+1)dx=xtan(x2+12)dx=tan(x2+12)d(x2+12)=log|sec(x2+12)|+C
Question 3. x4+11+x6 dx=
  1.    tan−1(x)−tan−1(x3)+c
  2.    tan−1(x)−13tan−1(x3)+c
  3.    tan−1(x)+tan−1(x3)+c
  4.    tan−1(x)+13tan−1(x3)+c
 Discuss Question
Answer: Option D. -> tan−1(x)+13tan−1(x3)+c
:
D
I=x4+11+x6dx=(x4x2+1)+x2(1+x6)dx=x4x2+11+x6dx+x21+x6dx=11+x2dx+133x21+x6dx=tan1(x)+13tan1x3+c
Question 4. cos3x+cos5xsin2x+sin4xdx equals
  1.    sinx−6tan−1(sinx)+c  
  2.    sinx−2sin−1x+c  
  3.    sinx−2(sinx)−1−6tan−1(sinx)+c  
  4.    sinx−2(sinx)−1+5tan−1(sinx)+c
 Discuss Question
Answer: Option C. -> sinx−2(sinx)−1−6tan−1(sinx)+c  
:
C
sinx=t;I=(1t2)(2t2)t2(1+t2)dt=(1+2t261+t2)dt
=sinx2(sinx)16tan1(sinx)+c
Question 5. If Φ(x)=dxsin12x cos72x, then Φ(π4)Φ(0)=
  1.    125
  2.    95
  3.    65
  4.    0
 Discuss Question
Answer: Option A. -> 125
:
A
tanx=tsec2xdx=dtf(x)=dxsin12xcos12x.cos4x=(1+tan2x)sec2xtanxdx=(1+t2)tdt=(t1/2+t3/2)dt=2t1/2+25t5/2=2tanx+25(tanx)5/2ϕ(π4)ϕ(0)=2+25=125
Question 6. If dxx1x3=a log1x311x3+1+C then a =
  1.    13
  2.    23
  3.    −13
  4.    −23
 Discuss Question
Answer: Option A. -> 13
:
A
Put<br> 1x3=t23x2dx=2tdtdxx1x3=x2x31x3dx=23dtt21=13logt1t+1+C=13log1x311x3+1+Ca=13
Question 7. dxcos(2x)cos(4x)is equal to
  1.    12√2log|1+√2 sin 2x1−√2 sin 2x|−12(log|sec 2x+tan 2x|)+C
  2.    12√2log|1+√2 sin 2x1+√2 sin 2x|−12(log|sec 2x+tan 2x|)+C
  3.    1√2log|1+√2 sin 2x1+√2 sin 2x|−12(log|sec 2x−tan 2x|)+C
  4.    None of these
 Discuss Question
Answer: Option A. -> 12√2log|1+√2 sin 2x1−√2 sin 2x|−12(log|sec 2x+tan 2x|)+C
:
A
sin(4x2x)dxsin(2x)cos(2x)cos(4x)=sin(4x)dxsin(2x)cos(4x)sec2xdx=2cos2xdxcos4x12(log|sec2x+tan2x|)
Question 8. ex[x3+x+1(1+x2)3/2]dx is equal to
  1.    x2ex(1+x2)1/2+c
  2.    exx(1+x2)1/2+c
  3.    ex(1+x2)1/2+c
  4.    xex(1+x2)1/2+c
 Discuss Question
Answer: Option D. -> xex(1+x2)1/2+c
:
D
I=ex[x1+x2+1(1+x2)3/2]dx
Let f(x)=x1+x2f(x)=1+x2x21+x2(1+x2)
=1(1+x2)3/2
I=exf(x)+c
=exx1+x2+c
Question 9. If cos 8x+1tan 2xcot 2xdx=a cos 8x+C, then
  1.    a=−116
  2.    a=18
  3.    a=116
  4.    a=−18
 Discuss Question
Answer: Option C. -> a=116
:
C
cos8x+1tan2xcot2xdx=2cos24xsin22xcos22x.sin2xcos2xdx=sin4xcos4xdx=12sin8xdx=116cos8x+Ca=116
Question 10. dxsin4x+cos4 x is equal to
  1.    1√2tan−1(1√2tan 2x)+C
  2.    √2tan−1(1√2tan 2x)+C
  3.    1√2tan−1(1√2cot 2x)+C
  4.    None of these
 Discuss Question
Answer: Option A. -> 1√2tan−1(1√2tan 2x)+C
:
A
dxsin4x+cos4x=dx(sin2x+cos2x)22sin2xcos2x=2dx2sin22x=2sec22x2sec22xtan22xdx=2sec22x2+tan22xdx=dt(2)2+t2[puttingtan2x=t2sec22xdx=dt]=12tan1(t2)+C=12tan1(12tan2x)+C

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