Q. Find the sum of the first 7 terms in the following geometric series. Do not round your answer.1024+512+256+…
Identify first term and common ratio: To find the sum of the first 7 terms of a geometric series, we need to identify the first term (a1) and the common ratio (r) of the series.The first term a1 is 1024.To find the common ratio, we divide the second term by the first term: r=1024512=21.
Calculate the common ratio: Now that we have the first term and the common ratio, we can use the formula for the sum of the first n terms of a geometric series: Sn=a1×(1−rn)/(1−r), where n is the number of terms.We want to find the sum of the first 7 terms, so n=7.
Use the formula for sum of first n terms: Let's plug the values into the formula: S7=1024×(1−(1/2)7)/(1−1/2).Now we calculate (1/2)7.
Plug in values into the formula:(21)7=1281.Now we substitute this value back into the sum formula: S7=1024×(1−1281)/(1−21).
Calculate (1/2)7: Simplify the expression inside the parentheses: 1−1/128=127/128. Now the sum formula looks like this: S7=1024×(127/128)/(1/2).
Substitute value into sum formula: We simplify the denominator: 1−21=21. Now we have S7=1024×(128127)/(21).
Simplify expression inside parentheses: To divide by 21, we multiply by the reciprocal, which is 2. So, S7=1024×(128127)×2.
Simplify the denominator: Now we perform the multiplication: 1024×2=2048. Then we multiply this by 127/128: S7=2048×(127/128).
Multiply by reciprocal: Finally, we calculate the multiplication: 2048×(127/128)=2048×127/128.
Perform multiplication: Perform the division: 2048×127/128=2048/128×127.2048/128=16.So, S7=16×127.
Perform division: Now we multiply 16 by 127 to get the final sum: S7=16×127=2032.