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Three number are in A.P. such that thei...

Three number are in A.P. such that their sum is
24 and sum of their squares is 224 . The number are

A

2, 8, 14 `

B

`4, 8, 12 `

C

6,8,12

D

5, 8, 11

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The correct Answer is:
To solve the problem, we need to find three numbers in Arithmetic Progression (A.P.) such that their sum is 24 and the sum of their squares is 224. ### Step-by-Step Solution: 1. **Assume the numbers in A.P.**: Let the three numbers be \( a - d \), \( a \), and \( a + d \), where \( a \) is the middle term and \( d \) is the common difference. 2. **Set up the equation for the sum**: The sum of these numbers is given by: \[ (a - d) + a + (a + d) = 3a = 24 \] From this, we can solve for \( a \): \[ 3a = 24 \implies a = \frac{24}{3} = 8 \] 3. **Set up the equation for the sum of squares**: The sum of the squares of these numbers is given by: \[ (a - d)^2 + a^2 + (a + d)^2 = 224 \] Substituting \( a = 8 \): \[ (8 - d)^2 + 8^2 + (8 + d)^2 = 224 \] 4. **Expand the squares**: Expanding the squares: \[ (8 - d)^2 = 64 - 16d + d^2 \] \[ 8^2 = 64 \] \[ (8 + d)^2 = 64 + 16d + d^2 \] Now, substituting these into the sum of squares: \[ (64 - 16d + d^2) + 64 + (64 + 16d + d^2) = 224 \] Simplifying this: \[ 64 - 16d + d^2 + 64 + 64 + 16d + d^2 = 224 \] \[ 192 + 2d^2 = 224 \] 5. **Solve for \( d^2 \)**: Rearranging gives: \[ 2d^2 = 224 - 192 \] \[ 2d^2 = 32 \implies d^2 = \frac{32}{2} = 16 \] Therefore, taking the square root: \[ d = \pm 4 \] 6. **Find the numbers**: Now we can find the three numbers for both cases of \( d \): - If \( d = 4 \): - The numbers are \( 8 - 4 = 4 \), \( 8 \), and \( 8 + 4 = 12 \). - If \( d = -4 \): - The numbers are \( 8 - (-4) = 12 \), \( 8 \), and \( 8 + (-4) = 4 \). 7. **Conclusion**: The three numbers in A.P. are \( 4, 8, 12 \) or \( 12, 8, 4 \). Thus, the answer is: **The numbers are 4, 8, and 12.**
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