Problems a through c are asking you what the values would be at those values.
What will the value of
be at
? Let's look at the graph.
It seems at
,
, meaning that
Let's do the same for the others.
At
,
At
,
For the last question, it is giving us the
value and asking us which
values would give us that.
At
,
.
*Note* this function is continuous to the right, meaning that there is another point where
.
Hope this helps.
頑張って!