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Consider the A.P. 50,48,46,44 ……. If S (...

Consider the A.P. `50,48,46,44 ……. If S _(n)` denotes the sum to n terms of this A.P. then

A

`S_(n) ` is maximum for n =25`

B

the first negative terms is `26^(th)` term

C

the first negative term is `27 ^(th)` term

D

the maximum value of `S_(n)` is 650

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To solve the problem step by step, we will analyze the given arithmetic progression (A.P.) and calculate the required values. ### Step 1: Identify the first term (A) and common difference (D) The given A.P. is: \[ 50, 48, 46, 44, \ldots \] - The first term \( A = 50 \) - The common difference \( D = 48 - 50 = -2 \) ### Step 2: Find the first term that is zero To find the first term that is zero, we can use the formula for the n-th term of an A.P.: \[ T_n = A + (n - 1)D \] Setting \( T_n = 0 \): \[ 0 = 50 + (n - 1)(-2) \] ### Step 3: Solve for n Rearranging the equation: \[ 50 - 2(n - 1) = 0 \] \[ 50 = 2(n - 1) \] \[ 25 = n - 1 \] \[ n = 26 \] Thus, the first term that is zero is the 26th term. ### Step 4: Determine the first negative term Since the 26th term is zero, the first negative term will be the 27th term: \[ T_{27} = 50 + (27 - 1)(-2) \] \[ T_{27} = 50 + 26(-2) \] \[ T_{27} = 50 - 52 = -2 \] So, the first negative term is the 27th term. ### Step 5: Find the maximum sum \( S_n \) The sum of the first n terms of an A.P. is given by: \[ S_n = \frac{n}{2} \left( 2A + (n - 1)D \right) \] To find when \( S_n \) is maximum, we note that since the 26th term is zero, the sum will be maximum at \( n = 25 \). ### Step 6: Calculate \( S_{25} \) Substituting \( n = 25 \): \[ S_{25} = \frac{25}{2} \left( 2 \times 50 + (25 - 1)(-2) \right) \] \[ S_{25} = \frac{25}{2} \left( 100 - 48 \right) \] \[ S_{25} = \frac{25}{2} \times 52 \] \[ S_{25} = 25 \times 26 = 650 \] ### Conclusion 1. The first negative term is the 27th term. 2. The sum \( S_n \) is maximum for \( n = 25 \). 3. The maximum value of \( S_{25} \) is 650. ### Final Options - Option 1: \( S_n \) is maximum for \( n = 25 \) (Correct) - Option 2: The first negative term is the 26th term (Incorrect) - Option 3: The first negative term is the 27th term (Correct) - Option 4: The maximum value of \( S_n \) is 650 (Correct) Thus, the correct options are 1, 3, and 4.
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