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f-x-f-1-1-x-tan-1-x-x-0-Find-f-x-




Question Number 145190 by qaz last updated on 03/Jul/21
f(x)+f(1−(1/x))=tan^(−1) x,(x≠0)  Find f(x)=?
f(x)+f(11x)=tan1x,(x0)Findf(x)=?
Answered by EDWIN88 last updated on 03/Jul/21
(1)f(x)+f(((x−1)/x))= tan^(−1) (x)   replace x→((x−1)/x)  (2)f(((x−1)/x))+f(((((x−1)/x)−1)/((x−1)/x)))=tan^(−1) (((x−1)/x))  ⇒f(((x−1)/x))+f((1/(1−x)))=tan^(−1) (((x−1)/x))  replace x→(1/(1−x))  (3)f((1/(1−x)))+f((((1/(1−x))−1)/(1/(1−x))))=tan^(−1) ((1/(1−x)))  ⇒f((1/(1−x)))+f(x)= tan^(−1) ((1/(1−x)))  sum equation (1),(2),(3)  ⇒2 [f(x)+f((1/(1−x)))+f(((x−1)/x))]=tan^(−1) (x)+tan^(−1) (((x−1)/x))+tan^(−1) ((1/(1−x)))  ⇒2 [f(x)+tan^(−1) (((x−1)/x))]=tan^(−1) (x)+tan^(−1) (((x−1)/x))+tan^(−1) ((1/(1−x)))  2f(x)=tan^(−1) (x)+tan^(−1) ((1/(1−x)))−tan^(−1) (((x−1)/x))  f(x)=(1/2)[ tan^(−1) (x)+tan^(−1) ((1/(1−x)))−tan^(−1) (((x−1)/x))]   =(1/2)[ tan^(−1) (((x+(1/(1−x)))/(1−(x/(1−x)))))−tan^(−1) (((x−1)/x))]  =(1/2)[ tan^(−1) (((x+1−x^2 )/(1−2x)))−tan^(−1) (((x−1)/x))]  =(1/2)tan^(−1) (((((x+1−x^2 )/(1−2x))−((x−1)/x))/(1+(((x+1−x^2 )(x−1))/((1−2x)x)))))  =(1/2)tan^(−1) (((x^2 +x−x^3 −(1−2x)(x−1))/(1−2x^2 +(x−1)(x+1−x^2 ))))
(1)f(x)+f(x1x)=tan1(x)replacexx1x(2)f(x1x)+f(x1x1x1x)=tan1(x1x)f(x1x)+f(11x)=tan1(x1x)replacex11x(3)f(11x)+f(11x111x)=tan1(11x)f(11x)+f(x)=tan1(11x)sumequation(1),(2),(3)2[f(x)+f(11x)+f(x1x)]=tan1(x)+tan1(x1x)+tan1(11x)2[f(x)+tan1(x1x)]=tan1(x)+tan1(x1x)+tan1(11x)2f(x)=tan1(x)+tan1(11x)tan1(x1x)f(x)=12[tan1(x)+tan1(11x)tan1(x1x)]=12[tan1(x+11x1x1x)tan1(x1x)]=12[tan1(x+1x212x)tan1(x1x)]=12tan1(x+1x212xx1x1+(x+1x2)(x1)(12x)x)=12tan1(x2+xx3(12x)(x1)12x2+(x1)(x+1x2))
Commented by qaz last updated on 03/Jul/21
thank you
thankyou

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