To find the 10th term of the sequence \(40, _, _, _, _, 10\), we first must identify a pattern or rule. Given the first term (40) and the last term (10), we can assume that this sequence decreases consistently.
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Identifying the common difference:
- The first term is 40, and the fifth term is 10.
- The number of terms between them, from 1 to 5, is 4 (counting 5 terms: 1 to 5).
- Therefore, the total decrease from 40 to 10 occurs over 4 intervals (the gaps between terms).
- The total decrease is: \[ 40 - 10 = 30 \]
- The common difference (d) is calculated as: \[ d = \frac{-30}{4} = -7.5 \]
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Finding intermediate terms:
- Now we can find the other terms in the sequence using this common difference.
- The second term: \[ 40 - 7.5 = 32.5 \]
- The third term: \[ 32.5 - 7.5 = 25 \]
- The fourth term: \[ 25 - 7.5 = 17.5 \]
- The fifth term (already known): \[ 17.5 - 7.5 = 10 \]
Putting it all together, the sequence so far is: \[ 40, 32.5, 25, 17.5, 10 \]
Now, to find the 10th term, we need to determine the value of \(a_n\) where \(n = 10\). We can use the formula for the nth term of an arithmetic sequence: \[ a_n = a_1 + (n-1) \cdot d \] where \(a_1 = 40\), \(d = -7.5\) and \(n = 10\): \[ a_{10} = 40 + (10-1) \cdot (-7.5) \] \[ a_{10} = 40 + 9 \cdot (-7.5) \] \[ a_{10} = 40 - 67.5 \] \[ a_{10} = -27.5 \]
Thus, the 10th term of the sequence is \(\boxed{-27.5}\).