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Evaluate the arithmetic series. Please help me!!!

Evaluate the arithmetic series. Please help me!!!-example-1

1 Answer

4 votes

Answer:

Explanation:

∑1 to 18 (5n-4)

a1=5×1-4=1

a2=5×2-4=6

a18=5×18-4=86

n=18


S_(n)=(n)/(2) (a1+an)\\S_(18)=(18)/(2) (1+86)=9 * 87=783

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