3 years ago

For an arithmetic sequence where a1 = 13 and the common difference is 3, find s7.

Mathematics

1 answer:

melamori03 [73]3 years ago

7 0

Answer:

Answer:

D ) 154

Step-by-step explanation:

a 1 = 13, d = 3;

S n = n/2 * ( a 1 + a n )

a 7 = a 1 + 6 d = 13 + 3 * 6 = 13 + 18 = 31

S 7 = 7/2 * ( 13 + 31 ) = 7/2 * 44 = 154

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What is the area of a triangle with a height of 13 cm and a base of a 10 cm?

Alecsey [184]

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