First slide
Evaluation of definite integrals
Question

Given two non -constant functions f and g which are integrable on every interval and satisfy

 (i) f is odd, g is even 

 (ii) g(x)=f(x+5), then which of the following are true ? 

Difficult
Solution

 To test choice (a) and (b), we begin with computting g(x). Indeed g(x)=f(x+5)  (From (ii) in ques.) 

g(x)=f(x+5)

g(x)=f(x5) (From (i) in question) 

 Choice (b) is true and choice (a) is ruled out. To test the choices (c) and (d), we compute

I=05f(t) dt  =05g(t5)dt     (f(t)=g(t5) on replacing x by t5 in (ii)) 

=05g(5-t)dt    (g is even ) Choice (c) is correct and choice (d) is false 

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