causal and time variant

[skan]

1.g(t) = f(t) + f(-t)
2. g(t)= f(t/2)
can someone pls explain why these functions are time variant and non causal

[Gokul43201]

This sounds like it's from a DSP course. Is it ? Are you talking about filters ?

[skan]

yeah I am !! they are filters.