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in an arithmetic sequence, the sum of the first n terms is s_n=n^2. find a_8
i'm not sure how to do this, so yeah

Sagot :

Answer:

[tex]a_{8} = 15[/tex]

Step-by-step explanation:

[tex]a_{1} + a_{2} + ..... + a_{7} + a_{8} = 8^{2} = 64[/tex]

[tex]-a_{1} - a_{2} ..... - a_{7} = - 7^{2} = -49[/tex]    Now add the two equations

                                 [tex]a_{8} = 64 - 49 = 15[/tex]

[tex]a_{8} = 15[/tex]

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