Answer:
Step-by-step explanation
(2/3) (60/99) = (2/99)(60/3) = (2/99)(20) = 40/99 = .040404......... So.......the sum of the first 15 digits = 7(4) + 7(0) + 0 = 28.
Answer:
3.75
Step-by-step explanation:
3.75 you couldve used calculator :/
an = a1r^(n-1)
a5 = a1 r^(5-1)
-6 =a1 r^4
a2 = a1 r^(2-1)
-48 = a1 r
divide
-6 =a1 r^4
---------------- yields 1/8 = r^3 take the cube root or each side
-48 = a1 r 1/2 = r
an = a1r^(n-1)
an = a1 (1/2)^ (n-1)
-48 = a1 (1/2) ^1
divide by 1/2
-96 = a1
an = -96 (1/2)^ (n-1)
the sum
Sn = a1[(r^n - 1/(r - 1)]
S18 = -96 [( (1/2) ^17 -1/ (1/2 -1)]
=-96 [ (1/2) ^ 17 -1 /-1/2]
= 192 * [-131071/131072]
approximately -192
This is the sum of the arithmetic sequence:
10 - 2 + 6 + 14 + ... + 110
where: a 1 = - 10, d = 8
a n = 110
a n = a 1 + ( n - 1 ) * d
110 = - 10 + ( n - 1 ) * 8
110 = - 10 + 8 n - 8
110 + 10 + 8 = 8 n
128 = 8 n
n = 128 : 8
n = 16
∑ n = n/2 * ( a 1 + a n )
∑ 16 = 16/2 * ( -10 + 110 ) = 8 * 100 = 800
Answer:
The sum is 800.
