It means that the composition of functions G and f is injective, but the function g itself is not injective.
An injective function is a function where each element in the domain maps to a unique element in the codomain.
No, a function cannot be both injective and not injective at the same time. It is either one or the other.
The difference lies in the composition of functions. G of f injective means the composition of G and f is injective, while g not injective means that the function g itself is not injective.
To determine if a function is injective, you can use the horizontal line test. If a horizontal line can intersect the graph of the function at more than one point, then the function is not injective.