392. d)?
1)if 
then the range of f(x) is?
2)if the function f(x)=sinx+cosax is periodic, then a must be
a)a rational number
b)an integer
c)any real number
d)irrational
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3 Answers
1062. for periodicity a must be rational (including integers as well) as period = LCM of period of sinx and period of cosax
= LCM(2pi, 2pi/a) which exists only if a is rational
1. If x=rational, then f(x) = 1
If x=irrational, tehn f(x) = 0
so range of f(x) = {0,1}