So, for number 3, its 2. and for number 4 its also 2
Answer:
y + 9 = 6(x - 4)
Step-by-step explanation:

must be continuous in order to be differentiable, so we need to have

By its definition,
, and


so that
.
We want the derivative to exist at
, which requires that we pick an appropriate value for
so that
is also continuous. At the moment, we know
such that

We have


so that
(which means we need to pick
) and so 