Recognize as geometric series: Recognize the series as a geometric series where the first term a=6 and the common ratio r=1.5. The sum of a finite geometric series can be calculated using the formula Sn=a1−r1−rn, where n is the number of terms.
Calculate number of terms: Calculate the number of terms n. Since the series starts at k=0 and goes up to k=19, there are 19−0+1=20 terms.
Substitute values into formula: Substitute the values into the sum formula for a geometric series. Here, a=6, r=1.5, and n=20. So, S20=61−1.51−(1.5)20.
Calculate sum: Calculate the sum S20. First, calculate (1.5)20 and then substitute it into the formula.
Handle negative denominator: Since r > 1 , the denominator 1−r is negative. Therefore, we need to be careful with the signs when calculating the sum. The correct formula application is S20=61−1.51−(1.5)20=6−0.51−(1.5)20.
Compute (1.5)^20: Compute (1.5)20 using a calculator.(1.5)20≈33219.476736
Substitute into formula and calculate: Substitute (1.5)20 into the sum formula and calculate S20.S20=6−0.51−33219.476736S20=6−0.5−33218.476736S20=6⋅66436.953472S20=398621.720832