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Explicit Formula Practice

Arithmetic sequence: 1, 3, 5, ...
aₙ = 2n - 1
34th Term: 67

Arithmetic sequence: -6, -10, -14, ...
aₙ = -4n - 2
27th Term: -110

Geometric sequence: 2, -6, 18, ...
aₙ = 2 * (-3)^(n-1)
4th Term: -54

Geometric sequence: 1, 4, 16, ...
aₙ = 4^(n-1)
7th Term: 256

1 Answer

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Final answer:

To find the 34th term of the arithmetic sequence 1, 3, 5,..., you can use the formula aₙ = 2n - 1. Substitute n = 34 to find a₃₄ = 67. For the geometric sequence 2, -6, 18,..., you can use the formula aₙ = 2 * (-3)^(n-1). Substitute n = 4 to find a₄ = -54.

Step-by-step explanation:

An arithmetic sequence is a sequence of numbers in which the difference between consecutive terms is constant. The formula to find the nth term of an arithmetic sequence is given by aₙ = a₁ + (n-1)d, where a₁ is the first term and d is the common difference.

For the first arithmetic sequence, aₙ = 2n - 1. To find the 34th term, substitute n = 34 into the formula:

a₃₄ = 2(34) - 1 = 67

For the second arithmetic sequence, aₙ = -4n - 2. To find the 27th term, substitute n = 27 into the formula:

a₂₇ = -4(27) - 2 = -110

A geometric sequence is a sequence of numbers in which the ratio between consecutive terms is constant. The formula to find the nth term of a geometric sequence is given by aₙ = a₁ * r^(n-1), where a₁ is the first term and r is the common ratio.

For the third geometric sequence, aₙ = 2 * (-3)^(n-1). To find the 4th term, substitute n = 4 into the formula:

a₄ = 2 * (-3)^(4-1) = -54

For the fourth geometric sequence, aₙ = 4^(n-1). To find the 7th term, substitute n = 7 into the formula:

a₇ = 4^(7-1) = 256

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