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Please help! this is for algebra 2. im not sure that im doing it correctly. thank you!

Please help! this is for algebra 2. im not sure that im doing it correctly. thank-example-1

1 Answer

5 votes
a) an = a1 + (n-1)d

so Sn = (n/2)[ a1 + ( a1 + (n-1)d)]
= (n/2) [ 2a1 + (n-1)d ]
= na1 + n(n-1)
-------- d
2



User Rod Talingting
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