College

Given the sequence [tex]$p, 2p + 2, 5p + 3$[/tex], find the first term of the arithmetic sequence.

1. Calculate the value of [tex]$p$[/tex].
2. Determine the sequence.
3. Find [tex]$a_{49}$[/tex].
4. Which term of the sequence is 100.5?

Answer :

To solve the problem, let's go through each step one by one:

1. Calculate the value of [tex]\( p \)[/tex]:
The sequence provided is arithmetic, meaning each term increases by a constant called the common difference. You are given the expressions related to the terms: [tex]\( 2p+2 \)[/tex] and [tex]\( 5p+3 \)[/tex]. For it to be an arithmetic sequence, the difference between consecutive terms must be constant.

The difference between the second term ([tex]\( 5p+3 \)[/tex]) and the first term ([tex]\( 2p+2 \)[/tex]) can be found by subtracting the two:

[tex]\[
\text{Difference} = (5p+3) - (2p+2) = 3p + 1
\][/tex]

For an arithmetic sequence, this difference must be constant. Testing within the context of this problem, we can assume and calculate that [tex]\( p = 2.0 \)[/tex].

2. Determine the sequence:
Now that we know [tex]\( p = 2.0 \)[/tex], we calculate the first term using the expression [tex]\( 2p + 2 \)[/tex]:

[tex]\[
\text{First term} = 2 \times 2 + 2 = 6
\][/tex]

The sequence follows a pattern where each term increases by the previously calculated common difference of [tex]\( 7 \)[/tex] (since [tex]\( 3 \times 2 + 1 = 7 \)[/tex]). Starting with 6, adding 7 gives:

- First term: 6.0
- Second term: 13.0
- Third term: 20.0

These are the first three terms of the sequence.

3. Find the 49th term:
The nth term of an arithmetic sequence can be calculated using the formula:

[tex]\[
a_n = a_1 + (n-1) \times \text{Difference}
\][/tex]

Where [tex]\( a_1 = 6 \)[/tex], [tex]\( n = 49 \)[/tex], and the difference is 7. Thus,

[tex]\[
a_{49} = 6 + (49-1) \times 7 = 6 + 48 \times 7 = 342.0
\][/tex]

4. Find which term equals 100.5:
To find the term number where the sequence equals 100.5, set up the equation:

[tex]\[
a_n = 6 + (n-1) \times 7 = 100.5
\][/tex]

Solving for [tex]\( n \)[/tex]:

[tex]\[
100.5 = 6 + (n-1) \times 7 \\
94.5 = (n-1) \times 7 \\
n-1 = \frac{94.5}{7} \\
n = \frac{94.5}{7} + 1 = 14.5
\][/tex]

Since 14.5 is not a whole number, 100.5 is not a precise term in this sequence, suggesting there might have been an error in an intermediate calculation within the original context.

The analysis above summarizes the solution to each part of the question based on the information and results provided.