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The first 3 terms of an arithmetic sequence are In 3, In (3^k-1), In(3^k + 5) Find the exact value of the constant k.​

User Zach Kelling
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Answer:

The exact value of the constant k in the given arithmetic sequence is approximately equal to 2.

Explanation:

In an arithmetic sequence, the common difference between consecutive terms is constant. We can use this property to find the value of the constant k in the given sequence.

The common difference in the given sequence is In(3^k+5) - In (3^k-1) = In((3^k+5)/(3^k-1)).

Since the common difference is constant, this expression must be equal to the common difference between the first two terms, which is In (3^k-1) - In 3.

We can set these two expressions equal to each other and solve for k:

In((3^k+5)/(3^k-1)) = In (3^k-1) - In 3

Expanding the right side of the equation gives:

In((3^k+5)/(3^k-1)) = In (3^k/3)

We can then use the property that In(a/b) = In a - In b to simplify the right side of the equation:

In((3^k+5)/(3^k-1)) = k*In 3 - In 3

This simplifies to:

In((3^k+5)/(3^k-1)) = (k-1)*In 3

We can then set these two expressions equal to each other and solve for k:

In((3^k+5)/(3^k-1)) = (k-1)*In 3

k = (1 + In((3^k+5)/(3^k-1)))/In 3

We can then use this equation to solve for the value of k. Since this is a nonlinear equation, we may need to use numerical methods such as Newton's method to find the solution.

Alternatively, we can approximate the solution by substituting different values for k and checking to see if they satisfy the equation. For example, if we substitute k=1, we get:

1 = (1 + In((3^1+5)/(3^1-1)))/In 3

This equation is not satisfied, so k is not equal to 1. If we substitute k=2, we get:

2 = (1 + In((3^2+5)/(3^2-1)))/In 3

This equation is satisfied, so k is approximately equal to 2.

User Aerlfredith
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