Which of the following correctly uses the explicit formula An=1/4+(n-1)•2, To find the 9th term of the described arithmetic sequence

11 answers

To find the 9th term of the arithmetic sequence using the explicit formula \( A_n = \frac{1}{4} + (n-1) \cdot 2 \), you simply need to substitute \( n = 9 \) into the formula.

  1. Substitute \( n = 9 \) into the formula:

    \[ A_9 = \frac{1}{4} + (9-1) \cdot 2 \]

  2. Simplify:

    \[ A_9 = \frac{1}{4} + 8 \cdot 2 \]

    \[ A_9 = \frac{1}{4} + 16 \]

  3. To add \( \frac{1}{4} \) and \( 16 \), convert \( 16 \) into a fraction:

    \[ 16 = \frac{64}{4} \]

  4. Now add the two fractions:

    \[ A_9 = \frac{1}{4} + \frac{64}{4} = \frac{1 + 64}{4} = \frac{65}{4} \]

So, the 9th term of the described arithmetic sequence is:

\[ A_9 = \frac{65}{4} \quad \text{or} \quad 16.25 \]

But could you turn that into a mixed number? Ty

Sure! To convert the improper fraction \(\frac{65}{4}\) into a mixed number, you divide the numerator by the denominator:

  1. Divide \(65\) by \(4\), which goes \(16\) times (since \(4 \times 16 = 64\)).
  2. Find the remainder: \(65 - 64 = 1\).

So, \(\frac{65}{4}\) can be expressed as:

\[ 16 \frac{1}{4} \]

Therefore, as a mixed number, \(A_9 = 16 \frac{1}{4}\).

That's not 1 of the answers I can put. I can pick 4 1⁄4, 8 1⁄4, 8 3⁄4, Or 4 3⁄4

Let's clarify the situation with the mixed number representation and the options provided.

We found that the 9th term \( A_9 \) is \( \frac{65}{4} \).

Converting \( \frac{65}{4} \) to a mixed number yields \( 16 \frac{1}{4} \), but this seems outside the options you've provided.

Since the options you have are:

  1. \( 4 \frac{1}{4} \)
  2. \( 8 \frac{1}{4} \)
  3. \( 8 \frac{3}{4} \)
  4. \( 4 \frac{3}{4} \)

It appears there may be a misunderstanding regarding the options based on either another term calculation or the sequence definition itself.

Re-checking the Calculation

To be completely accurate:

  1. We have the explicit formula: \[ A_n = \frac{1}{4} + (n-1) \cdot 2 \]

  2. For \( n = 9 \): \[ A_9 = \frac{1}{4} + (9-1) \cdot 2 = \frac{1}{4} + 8 \cdot 2 = \frac{1}{4} + 16 = \frac{1 + 64}{4} = \frac{65}{4} \] This gives us \( 16 \frac{1}{4} \) as confirmed.

If we were looking for the 4th term instead:

Calculating the 4th Term

\[ A_4 = \frac{1}{4} + (4-1) \cdot 2 = \frac{1}{4} + 3 \cdot 2 = \frac{1}{4} + 6 = \frac{1 + 24}{4} = \frac{25}{4} = 6 \frac{1}{4} \]

This is also not in your options.

Verifying Other Terms

If you want to see how it connects:

  • \( A_1 = \frac{1}{4} \)
  • \( A_2 = \frac{1}{4} + 2 = 2 \frac{1}{4} \)
  • \( A_3 = 2 \frac{1}{4} + 2 = 4 \frac{1}{4} \)
  • \( A_4 = 6 \frac{1}{4} \) (not included in options)

Let me clarify: You can only provide options 4 \( \frac{1}{4} \), 8 \( \frac{1}{4} \), 8 \( \frac{3}{4} \) or 4 \( \frac{3}{4} \). The original formula yields \(16.25\) or \(16 \frac{1}{4}\), which means if you made a mistake on the term number or if there was a check on the values being sought.

Final Verifications

Can you please confirm the \(n\) term you wish to evaluate? It may be that you need a different \(n\). The options \(4 \frac{1}{4}\), \(8 \frac{1}{4}\), \(8 \frac{3}{4}\), or \(4 \frac{3}{4}\) don’t match \(n = 9\).

N. equals 9 in this situation So I just needed you to calculate the equation with in being 9

Since \( n = 9 \) is confirmed, let's ensure we’re accurately determining the 9th term using the explicit formula \( A_n = \frac{1}{4} + (n-1) \cdot 2 \):

\[ A_9 = \frac{1}{4} + (9-1) \cdot 2 \]

Calculating step by step:

  1. Substitute \( n = 9 \) into the formula: \[ A_9 = \frac{1}{4} + (8) \cdot 2 \]

  2. Calculate \( 8 \cdot 2 \): \[ A_9 = \frac{1}{4} + 16 \]

  3. Combine the two terms. To do this, convert \( 16 \) into a fraction with the same denominator: \[ 16 = \frac{64}{4} \] So, \[ A_9 = \frac{1}{4} + \frac{64}{4} = \frac{1 + 64}{4} = \frac{65}{4} \]

Converting \( \frac{65}{4} \) into a mixed number:

  • \( 65 \div 4 = 16 \) with a remainder of \( 1 \), so: \[ A_9 = 16 \frac{1}{4} \]

Addressing Your Given Options

Since the outcome of \( A_9 \) as \( 16 \frac{1}{4} \) (or \( 16.25 \)) does not appear in your options, let’s reevaluate if there's confusion regarding the representation or available choices.

Given the options:

  1. \( 4 \frac{1}{4} \)
  2. \( 8 \frac{1}{4} \)
  3. \( 8 \frac{3}{4} \)
  4. \( 4 \frac{3}{4} \)

None align with the result we've calculated for \( n = 9 \). Thus, it's possible you may want to provide the context for those specific choices or verify the numbers or terms if they match.

If the explicit formula or the context were intended differently, please let me know. Based on \( n = 9 \), \( A_9 \) calculates firmly as \( 16 \frac{1}{4} \) or \( 16.25 \), not matching any given options.

OK well Can you give me your best guess That isn't 16 1⁄4

Given that \( A_9 \) calculated to \( 16 \frac{1}{4} \) (which is not among the choices you provided), I can suggest a possible misalignment in the options relative to what terms might be closely attainable.

Since you asked for an alternative guess among the options:

The closest values to \( 16 \frac{1}{4} \) are as follows:

  • \( 8 \frac{3}{4} \) is significantly lower.
  • \( 8 \frac{1}{4} \) is lower too.
  • \( 4 \frac{1}{4} \) and \( 4 \frac{3}{4} \) are also equivalent but lower.

Given that both \( 8 \frac{3}{4} \) and \( 8 \frac{1}{4} \) are quite lower than \( 16.25 \), the answer could possibly be an indication of choosing between the choices based on rounding:

Recommendation

If you want to choose the closest option relative to \( 16.25\), the best guess would be \( 8 \frac{3}{4} \) among the provided options, but please note that it's just a guess since it doesn't accurately represent what the 9th term yields according to the formula.

Feel free to verify any context or if there are adjustments needed for a specific term other than 9!

Yeah that's fine I just need to get this done

Understood! If you need to complete your task, I suggest going with \( 8 \frac{3}{4} \) as the best guess among the options provided, even though it doesn't match the calculated term for \( A_9 \).

If you have any further questions or need more assistance, feel free to ask. Good luck!