Question

Which is equivalent to the series shown?

12
Which expansion is equivalent to the summation
shown?
12
12
20 Σ
1
n=9 n=9
n +
n=9
X
1 1 1 1
20+9+10+11+12+
9 10 11 12
-
Σ (20n +
+
Ź 201n+ )
20
n
n-9
x
1
1
-
1
11
1
12
20(9 + 10 +11+12) +.
9 10
2019 +10 +1
X
1 1 1
20 9+10 +11+12+
9 10 11 12
n +
n-9
12 12
1
12 + 20
n
n=9 n-9
12 12
1
n+
n-9 n=9n
1 1 1
9+10+11+12+ 20
9 10 11 12
20Σ
COMPLETE
Na
Intro
Final

Answer 1

first one is (d) second one is (b)

Explanation: