Maths-
General
Easy
Question
If 
x sin x dx = – x cos x + 
, then =
- sin x + c
- cos x + c
- x cos x + c
- cos x – sin x + c.
The correct answer is: sin x + c
To find the value of α
Let I=xsinxdx
Let u=x
⇒du=dx
dv=sinxdx
⇒v=−cosx
I=−xcosx+cosxdx
I=−xcosx+sinx+c
I=xsinxdx=−xcosx+α
Comparing with I=−xcosx+sinx+c we have
α=sinx+c
I=−xcosx+cosxdx
cosxdxI=−xcosx+sinx+c
I=xsinxdx=−xcosx+α
xsinxdx=−xcosx+αComparing with I=−xcosx+sinx+c we have
α=sinx+c
Therefore, the value of α is sinx+c
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