Let f : (1, ) R be a function defined as f(x)= x-1x+1. Let fi+1(x)=f (fi(x) ), i=1, 2, , 25, where f1(x)=f(x). If g(x)+f26(x)=0, x (1, ), then the area of the region bounded by the curves y=g(x), 2y=2x-3, y=0 and x=4 is :
- 18+ e 2
- 14+ e 2
- 56+3 e 2
- 56+ e 2
Answer
(1) 18+ e 2
Solution
f2(x)=f(f(x))= x-1x+1-1 x-1x+1+1= -22x=- 1x
f4(x)=f2 (f2(x) )=- 1- 1x=x f4m+2=f2
26=4(6)+2 f26(x)=- 1x g(x)= 1x
2y=2x-3 meets y=0 at x= 32 and y= 1x where 2x2-3x-2=0 x=2 (as x>1), i.e. at (2, 12 )
[figure]
Area = 3/22 (x- 32 )dx+ 24 dxx
= 12 ( 12 )2+ e 42= 18+ e2
Answer: (1)