Assignment 2 (TMA2)
Question 6
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Question text
If the first term of an A.P is 67 and the common difference is -13. Then, the sum of the first 20 terms is ______.
Question 6 Select one:
-1301
-1130
-113
-130
To find the sum of an arithmetic progression (A.P), you can use the formula:
Sn = (n/2)(2a + (n-1)d)
Where Sn is the sum of the first n terms, a is the first term, and d is the common difference.
In this case, the first term (a) is 67 and the common difference (d) is -13. We want to find the sum of the first 20 terms (n = 20).
Plugging the values into the formula, we get:
Sn = (20/2)(2(67) + (20-1)(-13))
= (10)(134 + 19(-13))
= (10)(134 - 247)
= (10)(-113)
= -1130
Therefore, the sum of the first 20 terms is -1130.
The correct answer is: -1130