In an AP given a=8,a_n=62,S_n=210,find n and d.

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Solution

We know that Sn= (n/2)[a + l] where l is the last term or nth term
Hence 210 = (n/2)[8 + 62]
210 = (n/2)[70]
35n = 210
Therefore, n = 6
Recall an= a + (n - 1)d
Tht is 62 = 8 + 5d
54 = 5d
∴ d = 54/5

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In an AP given a=8,an=62,Sn=210,find n and d.

We know that Sn= (n/2)[a + l] where l is the last term or nth term Hence 210 = (n/2)[8 + 62] 210 = (n/2)[70] 35n = 210 Therefore, n = 6 Recall an= a + (n - 1)d Tht is 62 = 8 + 5d 54 = 5d ∴ d = 54/5

In an AP given a=8,a_n=62,S_n=210,find n and d.

We know that Sn= (n/2)[a + l] where l is the last term or nth term
Hence 210 = (n/2)[8 + 62]
210 = (n/2)[70]
35n = 210
Therefore, n = 6
Recall an= a + (n - 1)d
Tht is 62 = 8 + 5d
54 = 5d
∴ d = 54/5