This is a trick question. the answer is neither, they are both equivalent to one another :)
Answer:
The number under the fraction line tells how many equal parts the whole was broken into
The first term is -43.
Explanation:
an = a + (n - 1)d
a12 = a + 11d = 56, first equation
a21 = a + 20d = 101, second equation
Subtract the second equation from the first equation, cancelling +a and -a
11d - 20d = 56 - 101
-9d = -45
d = 5
Subtitute d into the first equation
a + 99 = 56
a = -43
a refers to the first term, hence the first term is -43.
I don’t know to be honest
Substitute 
and 
. Then the integral transforms to
Apply the power rule.
Now put the result back in terms of 
.
