Q. Find the sum of the first 10 terms of the following series, to the nearest integer.63,21,7,…Answer:
Identify Sequence Type: Identify whether the given sequence is geometric or arithmetic.The given sequence appears to reduce by a factor of 3 each time. This suggests that it is a geometric sequence.
Find Common Ratio: Identify the common ratio of the geometric sequence.To find the common ratio, divide the second term by the first term.6321=31Common Ratio: 31
Calculate Sum Formula: Use the formula for the sum of the first n terms of a geometric series to find the sum of the first 10 terms.The formula for the sum of a geometric series is Sn=a1×(1−rn)/(1−r), where Sn is the sum of the first n terms, a1 is the first term, r is the common ratio, and n is the number of terms.
Plug Values and Simplify: Plug the values into the formula to calculate the sum.S10=63×(1−(31)10)/(1−31)
Calculate (1/3)10: Simplify the expression to find the sum.S10=63×(1−(1/3)10)/(2/3)To simplify further, multiply the numerator and denominator by 3 to get rid of the fraction in the denominator.S10=63×3×(1−(1/3)10)/2
Perform Final Calculation: Calculate the value of (31)10 to find the sum.(31)10 is a very small number, so for the purpose of finding the sum to the nearest integer, we can approximate it to 0.S10≈63×3×(1−0)/2
Perform Final Calculation: Calculate the value of (31)10 to find the sum.(31)10 is a very small number, so for the purpose of finding the sum to the nearest integer, we can approximate it to 0.S10≈63×3×(1−0)/2Perform the final calculation.S10≈63×3/2S10≈189/2S10≈94.5Since we need to find the sum to the nearest integer, we round 94.5 to 95.