20 POINTS please explain well

The difference of course is the symbol between the f and g letters.

The circle notation means we're doing a function composition.

Writing is the same as saying where g is the inner function.

Here's an example

f(x) = x^2

g(x) = 3x

f( g(x) ) = ( g(x) )^2 ... note how x is replaced with g(x)

f( g(x) ) = ( 3x )^2

f( g(x) ) = 9x^2

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On the other hand, the dot notation means we multiply the f(x) and g(x) functions.

Going back to the previous example, we could say

the answer is the third / last answer

step-by-step explanation: