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Please help? ASAP!!!??? ALGEBRA 2??!!?
What is the 41st term of the arithmetic sequence where a1 = 15 and a15 = -41 ?
A) -157
B) -153
C) -149
D) -145
What is the sum of a 30-term arithmetic sequence where the first term is 74 and the last term is -100?
A) -468
B) -442
C) -416
D) -390
What is the 8th term of the geometric sequence 1, -4, 16, …?
A) 16,384
B) -4,096
C) 4,096
D) -16,384
What is the 7th term of the geometric sequence where a1 = -2 and a5 = -512?
A) -2,048
B) -8,192
C) 2,048
D) 8,192
1 Answer
- Pi R SquaredLv 79 years agoFavorite Answer
Hi,
What is the 41st term of the arithmetic sequence where a1 = 15 and a15 = -41 ?
a(n) = a(1) + d(n - 1)
-41 = 15 + d(15 - 1)
-41 = 15 + 14d
-56 = 14d
d = -4
a(n) = a(1) + d(n - 1)
a(41) = 15 - 4(41 - 1)
a(41) = 15 - 160
a(41) = -145
A) -157
B) -153
C) -149
D) -145 <==ANSWER
What is the sum of a 30-term arithmetic sequence where the first term is 74 and the last term is -100?
S(n) = n/2(a(1) + a(n))
S(30) = 30/2(74 - 100)
S(30) = 15(-26)
S(30) = -390
A) -468
B) -442
C) -416
D) -390 <==ANSWER
What is the 8th term of the geometric sequence 1, -4, 16, …?
a(n) = a(1)r^(n - 1)
a(8) = 1(-4)^(8 - 1)
a(8) = -16,384
A) 16,384
B) -4,096
C) 4,096
D) -16,384 <==ANSWER
What is the 7th term of the geometric sequence where a1 = -2 and a5 = -512?
a(n) = a(1)r^(n - 1)
a(5) = a(1)r^(5 - 1)
-512 = -2r^4
256 = r^4
r = 4
a(n) = a(1)r^(n - 1)
a(7) = -2(4)^(7 - 1)
a(7) = -2(4)^6
a(7) = -8,192
A) -2,048
B) -8,192 <==ANSWER
C) 2,048
D) 8,192
I hope that helps!! :-)