Q. 9. Find the sum of the first 6 terms of the sequence 3 , 6,12,…A. 189C. 141B. 188D. 187
Identify type of sequence: Identify the type of sequence. The sequence is geometric because each term is multiplied by a common ratio.
Find common ratio: Find the common ratio. Common ratio = 36=2
Write sum formula: Write the formula for the sum of the first n terms of a geometric sequence. Sum = a⋅r−1rn−1 where a = first term, r = common ratio, n = number of terms
Plug in values: Plug in the values. a=3, r=2, n=6 Sum = 3imes2−126−1