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If `f(x) = int(5x^(8)+7x^(6))/((x^(2)+1+2x^(7))^(2))dx, (x ge 0)`, and f(0) = 0, then the value of f(1) isA. `-1//2`B. `1//4`C. `1//2`D. `-1//4` |
Answer» Correct Answer - B `f(x)=int(5x^(8)+7x^(6))/(x^(14)(2+(1)/(x^(7))+(1)/(x^(5)))^(2))dx` `=int((5)/(x^(6))+(7)/(x^(8)))/((2+(1)/(x^(7))+(1)/(x^(5)))^(2))dx` `"Put, "2+(1)/(x^(7))+(1)/(x^(5))=t` `rArr" "f(x)=-int(dt)/(t^(2))` `=(1)/(t)+c` `=((x^(7))/(2x^(7)+x^(2)+1))+c` `" "f(0)=0` `rArr" "c=0` `rArr" "f(x)=((x^(7))/(2x^(7)+x^(2)+1))` `rArr" "f(1)=(1)/(4)` |
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