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 ?
f(x−5)=g(x)
f(x−5)=−g(x)
∫05 f(t)dt=∫05 g(5−t)dt
∫05 f(t)dt=−∫05 g(5−t)dt
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(x−5) (From (i) in question)
⇒ Choice (b) is true and choice (a) is ruled out. To test the choices (c) and (d), we compute
I=∫05 f(t) dt =∫05 g(t−5)dt (∵f(t)=g(t−5) on replacing x by t−5 in (ii))
=∫05 g(5-t)dt (∵g is even )⇒ Choice (c) is correct and choice (d) is false