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If the sum and product of the first three terms in an AP are 33 and 1155, respectively, then a value of its 11th term is

A

`-25`

B

`-36`

C

`-35`

D

25

Text Solution

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The correct Answer is:
To solve the problem, we need to find the 11th term of an arithmetic progression (AP) given the sum and product of the first three terms. ### Step-by-Step Solution: 1. **Define the first three terms of the AP**: Let the first three terms of the AP be \( a - d, a, a + d \). 2. **Use the sum of the terms**: The sum of the first three terms is given as 33: \[ (a - d) + a + (a + d) = 3a = 33 \] From this, we can solve for \( a \): \[ 3a = 33 \implies a = 11 \] 3. **Use the product of the terms**: The product of the first three terms is given as 1155: \[ (a - d) \cdot a \cdot (a + d) = 1155 \] Substituting \( a = 11 \): \[ (11 - d) \cdot 11 \cdot (11 + d) = 1155 \] This simplifies to: \[ 11 \cdot (11^2 - d^2) = 1155 \] \[ 11 \cdot (121 - d^2) = 1155 \] Dividing both sides by 11: \[ 121 - d^2 = 105 \] Rearranging gives: \[ d^2 = 121 - 105 = 16 \] Taking the square root: \[ d = 4 \quad \text{or} \quad d = -4 \] 4. **Find the 11th term**: The 11th term of the AP is given by: \[ a + 9d \] We will calculate this for both values of \( d \). - For \( d = 4 \): \[ a + 9d = 11 + 9 \cdot 4 = 11 + 36 = 47 \] - For \( d = -4 \): \[ a + 9d = 11 + 9 \cdot (-4) = 11 - 36 = -25 \] 5. **Conclusion**: The possible values for the 11th term are 47 and -25. The question asks for a value of the 11th term, so we can state: \[ \text{A value of the 11th term is } -25. \]

To solve the problem, we need to find the 11th term of an arithmetic progression (AP) given the sum and product of the first three terms. ### Step-by-Step Solution: 1. **Define the first three terms of the AP**: Let the first three terms of the AP be \( a - d, a, a + d \). 2. **Use the sum of the terms**: ...
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