A)

is continuous, so

is also continuous. This means if we were to integrate

, the same constant of integration would apply across its entire domain. Over

, we have

. This means that

For

to be continuous, we need the limit as

to match

. This means we must have
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Now, over

, we have

, so

, which means
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.
b) Integrating over [1, 3] is easy; it's just the area of a 2x2 square. So,

c)

is increasing when

, and concave upward when

, i.e. when

is also increasing.
We have

over the intervals

and

. We can additionally see that

only on

and

.
d) Inflection points occur when

, and at such a point, to either side the sign of the second derivative

changes. We see this happening at

, for which

, and to the left of

we have

decreasing, then increasing along the other side.
We also have

along the interval

, but even if we were to allow an entire interval as a "site of inflection", we can see that

to either side, so concavity would not change.