1.

If `f((3x-4)/(3x+4))=x+2`, then `int` f(x)dx is equal toA. `e^(x+2)log_(e)|(3x-4)/(3x+4)|`B. `-(8)/(3)log_(e)|1-x|+(2)/(3)x+C`C. `(8)/(3)log_(e)|x-1|+(x)/(3)+C`D. none of these

Answer» Correct Answer - b
We have , `f((3x-4)/(3x+4))=x+2`
Let `(3x-4)/(3x+4)=alpha`
` rArr ((3x-4)+(3x+4))/((3x-4)-(3x+4))=(alpha+1)/(alpha-1)`
`rArr(6x)/(-8)=(alpha+1)/(alpha-1)`
`rArrx=-(4)/(3)((alpha+1)/(alpha-1))`
`rArrx+2=-(4alpha+4)/(3alpha-3)+2=(-4alpha-4+6alpha-6)/(3alpha-3)=(2alpha-10)/(3alpha-3)`
`becausef((3x-4)/(3a+4))=x+2`
`rArrf(alpha)=(2alpha-10)/(3alpha-3)`
`rArrf(alpha)=(2)/(3)((alpha-5)/(alpha-1))`
`rArrf(alpha)=(2)/(3)((alpha-1-4)/(alpha-1))=(2)/(3)(1-(4)/(alpha-1))=(2)/(3)-(8)/(3(alpha-1))`
`rArrf(x)=(2)/(3)-(8)/(3(x-1))`
`rArr intf(x)dx=int{(2)/(3)-(8)/(3(x-1))}dx`
`becauseintf(x)dx=(2)/(3)x-(8)/(3)log_(e)|x-1|+C`


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