Integrals: 2 marks Questions (CBSE Class 12)
14 different 2 marks questions on Integrals from CBSE Class 12 Maths board exams 2024–2026, newest first.
Evaluate : ∫04π1+sin2xdx
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Answer: 1
- 1+sin2x=sin2x+cos2x+2sinxcosx=(sinx+cosx)2.
- On [0,4π], sinx+cosx>0, so 1+sin2x=sinx+cosx.
- ∫04π(sinx+cosx)dx=[−cosx+sinx]04π.
- =(−21+21)−(−1+0)=1.
Evaluate : ∫0πsinxsin2pxdx, p ∈ N.
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Answer: 0
- Let I=∫0πsinxsin2pxdx.
- Using ∫0af(x)dx=∫0af(a−x)dx: I=∫0πsin(π−x)sin(2pπ−2px)dx.
- Since p∈N, sin(2pπ−2px)=−sin2px, and sin(π−x)=sinx.
- So I=−∫0πsinxsin2pxdx=−I.
- 2I=0, hence I=0.
Find : ∫2x3ex2dx.
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Answer: ex2(x2−1)+C
- Put x2=t, so 2xdx=dt.
- ∫2x3ex2dx=∫x2ex2⋅2xdx=∫tetdt.
- By parts: ∫tetdt=tet−∫etdt=tet−et+C.
- =ex2(x2−1)+C.
Find :
∫x1+2xdx
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Answer: 101(1+2x)25−61(1+2x)23+C
- Put 1+2x=t, so x=2t−1 and dx=2dt.
- I=∫2t−1t2dt=41∫(t23−t21)dt.
- =41(52t25−32t23)+C.
- =101(1+2x)25−61(1+2x)23+C.
Evaluate :
∫04π2xsinxdx
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Answer: 2
- Put x=t, so 2xdx=dt; when x=0, t=0 and when x=4π2, t=2π.
- I=2∫02πsintdt=2[−cost]02π.
- =2(0+1)=2.
Find :
∫e4x+1e4x−1dx
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Answer: 21log(e2x+e−2x)+C
- Divide numerator and denominator by e2x: integrand =e2x+e−2xe2x−e−2x.
- Put t=e2x+e−2x, dt=2(e2x−e−2x)dx.
- Integral =21∫tdt=21log∣t∣+C=21log(e2x+e−2x)+C.
Evaluate :
∫0a3x6+a6x2dx
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Answer: 3a31tan−1(a6) (for a > 0)
- Put t=x3, dt=3x2dx; x = 0 gives t = 0 and x=a3 gives t=a9.
- I=31∫0a9t2+(a3)2dt=31⋅a31[tan−1a3t]0a9.
- I=3a31tan−1(a6).
Evaluate :
∫0π/2sin2xcos3xdx
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Answer: −52
- sin2xcos3x=21[sin5x+sin(−x)]=21[sin5x−sinx].
- ∫0π/2=21[−5cos5x+cosx]0π/2.
- =21[(0+0)−(−51+1)]=21(−54)=−52.
Given dxdF(x)=2x−x21 and F(1) = 0, find F(x).
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Answer: F(x)=sin−1(x−1)
- 2x−x2=1−(x−1)2.
- F(x)=∫1−(x−1)2dx=sin−1(x−1)+C.
- F(1)=sin−10+C=0, so C=0.
- F(x)=sin−1(x−1).
Find : ∫x(x2−1)1dx.
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Answer: 21logx2x2−1+C
- x(x−1)(x+1)1=xA+x−1B+x+1C.
- x=0: A=−1; x=1: B=21; x=−1: C=21.
- Integral =−log∣x∣+21log∣x−1∣+21log∣x+1∣+C
- =21log∣x2−1∣−log∣x∣+C=21logx2x2−1+C.
Evaluate : ∫2−121cosx⋅log(1−x1+x)dx
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Answer: 0
- Let f(x)=cosx⋅log(1−x1+x).
- f(−x)=cosx⋅log(1+x1−x)=−cosx⋅log(1−x1+x)=−f(x), so f is odd.
- The integral of an odd function over [−21,21] is 0.
Find : ∫(x2+1)(x2−4)2xdx.
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Answer: 51logx2+1x2−4+C
- Put x2=t, 2xdx=dt: integral =∫(t+1)(t−4)dt.
- (t+1)(t−4)1=51(t−41−t+11).
- Integral =51log∣t−4∣−51log∣t+1∣+C=51logx2+1x2−4+C.
Find : ∫cos3xelogsinxdx
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Answer: −4cos4x+C
- elogsinx=sinx, so the integral is ∫cos3xsinxdx.
- Put t=cosx, dt=−sinxdx: −∫t3dt=−4t4+C.
- =−4cos4x+C.
Find : ∫5+4x−x21dx
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Answer: 61log5−x1+x+C
- 5+4x−x2=9−(x−2)2=32−(x−2)2.
- ∫32−(x−2)2dx=2⋅31log3−(x−2)3+(x−2)+C.
- =61log5−x1+x+C.
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