The question is to find the solution to and domain of fgx an
The question is to find the solution to and domain of f(g(x)) and g(f(x)) where f(x) =sin 2x and g(x) = 1/x. I\'m confused. I think the answers are f(g(x)) = sin 2/x and g(f(x)) = 1/sin 2x and the domain being any points which would cause the denominator to be zero. But, that seems way too easy. What am I missing?
Solution
You aint missing anything :P
For sinx, x lies between -pi/2 to pi/2
so, for sin(2/x) , 2/x lies between -pi/2 to pi/2
or, 1/x lies between -pi/4 to pi/4
or, x lies between -4/pi to 4/pi excluding 0
For 1/x, domain is R-{0}
So, for 1/sin2x, sin2x not =0
and for sin2x, domain is -pi/4 to pi/4
So, domain will be -pi/4 to pi/4 excluding 0
