Composition of continuous maps is continuous

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mikki
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Suppose that f: D-->R and g: R-->Y are two continuous transfromations, where D, R, and Y are subsets of the plane. Show that the composition
g o f is a continuous transformation.
 
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mikki said:
Show that the composition g o f is a continuous transformation.

Who are you talking to? Show some work if you want some help.
 
mikki said:
Suppose that f: D-->R and g: R-->Y are two continuous transfromations, where D, R, and Y are subsets of the plane. Show that the composition
g o f is a continuous transformation.

it doesn't take much to prove that. if you just write down the definitions i think you'll have done half the work. what have you tried so far?
 
What definition of "continuous" are you using? There are several equivalent ones. The most common is "f is continuous if and only if for every open set U in the range, f-1(U) is an open set in the domain. What is (gof)-1?
 
HallsofIvy said:
What definition of "continuous" are you using? There are several equivalent ones. The most common is "f is continuous if and only if for every open set U in the range, f-1(U) is an open set in the domain. What is (gof)-1?

thats what i was getting at. consider f-1[g-1(U)] & it's pretty much done