If a1 a2.....an form an AP in which an=4+5n Find the sum of first 20 terms
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Answered by
0
Answer:
1130
Step-by-step explanation:
Given, an = 4 + 5n
Hence, a1 = 4 + 5x1 = 9
and, a2 = 4 + 5x2 = 14
Thus, first term = a = 9
and, common difference = d = a2 - a1 = 14 - 9 = 5
Sum of first 20 terms =
= (n/2){2a + (n-1)d}
= (20/2){2x9 + (20-1)x5}
= 10{18 + 95}
= 1130
Answered by
0
Answer:
Sum of first 20 terms = 1,130
See the attached image for detailed steps
Step-by-step explanation:
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