I had this question which I could not figure out myself, if you could at least guide me in it, it would be good. The question says: The output y(t) of a system is related to its input x(t) by
$$y(t)=\int h(t, t') x(t')dt'$$
The integral limits are from $-\infty$ to $\infty$
How would I know if the system is linear and also time-invariant?