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Question Number 47364 by olj55336@awsoo.com last updated on 09/Nov/18

        anybody please help  q...∫cos^(−1) (√x) dx

anybodypleasehelpq...cos1xdx

Commented by maxmathsup by imad last updated on 09/Nov/18

changement (√x)=t give I =∫ arccos((√x))=∫2t arcos(t)dt    =_(by parts)     t^2 arcost +∫ t^2   (dt/(√(1−t^2 ))) but  ∫  (t^2 /(√(1−t^2 )))dt = ∫ t .(t/(√(1−t^2 )))dt =_(by parts)    −t (√(1−t^2 ))−∫ (√(1−t^2 ))dt and  ∫ (√(1−t^2 ))dt =_(t=sinu)   ∫ cosu cosu du =∫((1+co(2u))/2)  =(u/2) +(1/4)sin(2u) =(u/2)+(1/2)sinu cosu =(1/2)arcsint  +(1/2)t(√(1−t^2 )) ⇒  ∫ arcos((√x)) = xarcos((√x))−(√x)(√(1−x))−(1/2) arcsin((√x))−(1/2)(√x)(√(1−x)) +C  =xarcos((√x))−(3/2)(√x)(√(1−x))−(1/2)arcsin((√x)) +C .

changementx=tgiveI=arccos(x)=2tarcos(t)dt=bypartst2arcost+t2dt1t2butt21t2dt=t.t1t2dt=bypartst1t21t2dtand1t2dt=t=sinucosucosudu=1+co(2u)2=u2+14sin(2u)=u2+12sinucosu=12arcsint+12t1t2arcos(x)=xarcos(x)x1x12arcsin(x)12x1x+C=xarcos(x)32x1x12arcsin(x)+C.

Answered by Smail last updated on 09/Nov/18

A=∫cos^(−1) ((√x))dx  by parts  u=cos^(−1) ((√x))⇒u′=−(1/(2(√x)))×(1/(√(1−x)))  v′=1⇒v=x  A=xcos^(−1) ((√x))+(1/2)∫(√(x/(1−x)))dx  B=∫(√(x/(1−x)))dx  t=(√(x/(1−x)))⇒2tdt=(1/((1−x)^2 ))dx  x=(t^2 /(t^2 +1))  B=∫t×(2t(1−(t^2 /(t^2 +1)))^2 dt  =2∫(t^2 /((t^2 +1)^2 ))dt  t=tanu⇒dt=(1+tan^2 u)du  (dt/((1+t^2 )^2 ))=(du/(1+tan^2 u))  B=2∫tan^2 u×cos^2 udu=2∫sin^2 udu  =∫(1−cos(2u))du  =u−((sin(2u))/2)+c=u−sin(u)cos(u)+c  B=tan^(−1) (t)−(t/(1+t^2 ))+c=tan^(−1) ((√(x/(1−x))))−(√(x(1−x)))+c  A=xcos^(−1) ((√x))+(1/2)tan^(−1) ((√(x/(1−x))))−(1/2)(√(x(1−x)))+C

A=cos1(x)dxbypartsu=cos1(x)u=12x×11xv=1v=xA=xcos1(x)+12x1xdxB=x1xdxt=x1x2tdt=1(1x)2dxx=t2t2+1B=t×(2t(1t2t2+1)2dt=2t2(t2+1)2dtt=tanudt=(1+tan2u)dudt(1+t2)2=du1+tan2uB=2tan2u×cos2udu=2sin2udu=(1cos(2u))du=usin(2u)2+c=usin(u)cos(u)+cB=tan1(t)t1+t2+c=tan1(x1x)x(1x)+cA=xcos1(x)+12tan1(x1x)12x(1x)+C

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