Question

Find the sum of the first 18 terms of an AP 12b, 8b, ​

Answer 1

Answer:

396b

Step-by-step explanation:

$a = 12b\\ d = - 4b \\ s _{18} = \frac{18}{2} (2(12b) + 17( - 4b))$

$= 396b$

Answer 2

Answer:

Step-by-step explanation:

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