Q. Find the sum of the first 7 terms of the following series, to the nearest integer.6,9,227,…Answer:
Identify Pattern: The given series is not an arithmetic or geometric series, but we can observe a pattern in the first three terms. The first term is 6, the second term is 9 which is 1.5 times the first term, and the third term is (27/2) which is 1.5 times the second term. This suggests that each term is 1.5 times the previous term, indicating that the series is a geometric series with the first term a=6 and the common ratio r=1.5.
Apply Geometric Series Formula: To find the sum of the first 7 terms of a geometric series, we use the formula for the sum of the first n terms of a geometric series, which is Sn=a(1−rn)/(1−r), where a is the first term, r is the common ratio, and n is the number of terms.
Substitute Values: We will now apply the formula with a=6, r=1.5, and n=7 to find the sum of the first 7 terms.S7=(1−1.5)6(1−1.57)
Calculate Exponent: Calculating the value of 1.57 and then substituting it into the formula.1.57≈17.0859375S7=(1−1.5)6(1−17.0859375)
Perform Subtraction: Now, we will perform the subtraction in the numerator and the denominator. S7=(−0.5)6(−16.0859375)
Calculate Sum: Finally, we will calculate the sum by performing the multiplication and division.S7=−0.5−96.515625S7≈193.03125
Round to Nearest Integer: Since we need to find the sum to the nearest integer, we will round 193.03125 to the nearest integer.S7≈193
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