Question

For the given sequence, an=2-(n-1). find the sum of first 50 terms.​

Answer 1

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The sum of the first n terms of a sequence is given by Sn = n(n+2). Can you find the first three terms of the sequence?

Start with S1 = 1*(1+2) = 1*3 = 3. So the first term is 3.

Next, S2 = 2(2+2) = 2*4 = 8. This the sum of the first two terms. Since the first term is 3, the second term is 8–3 = 5.

Next, S3 = 3(3+2) = 3*5 = 15. This the sum of the first three terms. Since the sum of the first two terms is 8, the third term is 15–8 = 7.

Hence the first three terms are: 3, 5, and 7.

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Answer 2

Start with S1 = 1*(1+2) = 1*3 = 3. So the first term is 3.

Start with S1 = 1*(1+2) = 1*3 = 3. So the first term is 3.

Next, S2 = 2(2+2) = 2*4 = 8. This the sum of the first two terms.

Since the first term is 3, the second term is 8–3 = 5.

Step-by-step explanation:

Hope it will helpful for you thanks..‹•.•›