if the sum of n terms of the sequence 6 + 9+12+ ...120, find n
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Answer:
147 is the ans
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Answer:
S(n) = n/2 [2×6 + (n-1)×3]
⇒ S(n) = n/2 [12 + 3n - 3]
⇒ S(n) = n/2 [9 + 3n]
Step-by-step explanation:
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