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The sum of a geometric sequence is a(1-rn)/(1-r) In this case, a = 8, r = -2 and n=15 So the sum is 8(1-(-2)15)/(1+2) =8(1+32768)/3 =87,384 So the sum of the first 15 terms of the sequence 8, -16, 32, -64.... is 87,384.
LCM(15, 17, 45) = 765
765
The sum of the first 5 numbers is 15. 1+2+3+4+5=15
The sum of the first 15 positive even numbers is 240. (Simply square 15, then add 15 to the result: 15 x 15 = 225. 225 + 15 = 240).
For an Arithmetic Progression, Sum = 15[a + 7d].{a = first term and d = common difference} For a Geometric Progression, Sum = a[1-r^15]/(r-1).{r = common ratio }.
Sum of the first 15 positive integers is 15*(15+1)/2 = 120 Sum of the first 15 multiples of 8 is 8*120 = 960
the sum of the first 15 prime numbers is 328 .
The sum of a geometric sequence is a(1-rn)/(1-r) In this case, a = 8, r = -2 and n=15 So the sum is 8(1-(-2)15)/(1+2) =8(1+32768)/3 =87,384 So the sum of the first 15 terms of the sequence 8, -16, 32, -64.... is 87,384.
LCM(15, 17, 45) = 765
x is the first term and d is the difference then x + 3d = 15 and sum of first five terms isx + (x+d) + (x+2d) + (x+3d) + (x+4d)so 5x + 10d = 55 ie x + 2d = 11As x + 3d = 15, d = 4 and x = 3,giving the five terms as 3, 7, 11, 15 and 19
765
The sum of the smallest 15 positive integers is 120. The sum of the smallest 15 negative integers is -120.
6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72, 78, 84, 90.
The sum of the first 5 numbers is 15. 1+2+3+4+5=15
Factor the sum of terms as product of the GCC and a sum of 10t+15
The sum of the first 15 odd numbers is 225.