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"Let "int e^(x){f(x)-f'(x)}dx=phi(x). " ...

`"Let "int e^(x){f(x)-f'(x)}dx=phi(x). " Then "int e^(x) f(x)dx " is "`

A

`phi(x)+e^(x)f(x)`

B

`phi(x)-e^(x)f(x)`

C

`(1)/(2){phi(x)-e^(x)f'(x)}`

D

`(1)/(2){phi(x)+e^(x)f'(x)}`

Text Solution

Verified by Experts

The correct Answer is:
c

We know that `inte^(x){f(x)+f'(x)}dx=e^(x)f(x)` It is given that
`int e^(x){f(x)-f'(x)}dx=phi(x)`
Adding these two , we get
`2inte^(x)f(x)dx=phi(x)+e^(x)f(x)`
`rArrinte^(x)f(x)dx=(1)/(2){phi(x)+e^(x)f(x)}`
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OBJECTIVE RD SHARMA ENGLISH-INDEFINITE INTEGRALS-Solved Example
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  6. If n is an odd positive integer, then int|x^(n)|dx is equal to

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  7. If inte^(ax)cosbx dx=(e^(2x))/(29)f(x)+C , then f'' (x)=

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  8. int(sin^(4)x)/(sin^(4)x+cos^(4)x)dx is equal to

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  9. If intf(x)dx=2 {f(x)}^(3)+C , then f (x) is

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  14. Let f(x) be a polynomial of degree three f(0) = -1 and f(1) = 0. Also,...

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  15. int(1)/(x(1+root(3)(x))^(2))dxis equal to

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  16. Let f(x)=int(x^(2)dx)/((1+x^(2))(1+sqrt(1+x^(2))))and f(0)=0. f(x) i...

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  17. Let f(x) be a polynomial satisfying f(0)=2 , f'(0)=3 and f''(x)=f(x) t...

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