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Statement 1 : If a+2b+3c=1 and a gt 0 , ...

Statement 1 : If `a+2b+3c=1 and a gt 0 , b gt 0 , c gt 0 ` then the greatest value of `a^(3)b^(2)c` is `1/(5184)`
Statement 2 : There exists an A.P such that sum up of its n terms is given by `S_(n) = an^(3) +bn^(2) +cn+d`

A

Statement - 1 is Trus , Statement - 2 is True , Statement - 2 is a correct explanation for Statement - 1

B

Statement - 1 I True , Statement - 2 is True Statement - 2 is Not a correct explanation for statement - 1

C

Statement - 1 is True , Statement - 2 is False

D

Statement - 1 is False , Statement - 2 is True

Text Solution

AI Generated Solution

The correct Answer is:
To solve the given problem, we will analyze both statements step by step. ### Step 1: Analyze Statement 1 We are given the equation: \[ a + 2b + 3c = 1 \] with the conditions \( a > 0 \), \( b > 0 \), and \( c > 0 \). We need to find the maximum value of the expression: \[ E = a^3 b^2 c \] ### Step 2: Apply the Method of Lagrange Multipliers To maximize \( E \) subject to the constraint \( g(a, b, c) = a + 2b + 3c - 1 = 0 \), we can use the method of Lagrange multipliers. We set up the equations: \[ \nabla E = \lambda \nabla g \] where \( \nabla E = \left( \frac{\partial E}{\partial a}, \frac{\partial E}{\partial b}, \frac{\partial E}{\partial c} \right) \) and \( \nabla g = \left( \frac{\partial g}{\partial a}, \frac{\partial g}{\partial b}, \frac{\partial g}{\partial c} \right) \). Calculating the gradients: \[ \frac{\partial E}{\partial a} = 3a^2 b^2 c, \quad \frac{\partial E}{\partial b} = 2a^3 b c, \quad \frac{\partial E}{\partial c} = a^3 b^2 \] \[ \frac{\partial g}{\partial a} = 1, \quad \frac{\partial g}{\partial b} = 2, \quad \frac{\partial g}{\partial c} = 3 \] Setting up the equations: \[ 3a^2 b^2 c = \lambda, \quad 2a^3 b c = 2\lambda, \quad a^3 b^2 = 3\lambda \] ### Step 3: Solve the Equations From the equations, we can express \( \lambda \): 1. From \( 3a^2 b^2 c = \lambda \) 2. From \( 2a^3 b c = 2\lambda \) implies \( \lambda = a^3 b c \) 3. From \( a^3 b^2 = 3\lambda \) Setting the expressions for \( \lambda \) equal to each other: \[ 3a^2 b^2 c = a^3 b c \implies 3b = a \quad (1) \] \[ 3a^2 b^2 c = \frac{1}{3} a^3 b^2 \implies 3c = a \quad (2) \] ### Step 4: Substitute Back into the Constraint Substituting \( a = 3b \) and \( a = 3c \) into the constraint: \[ 3b + 2b + 3\left(\frac{b}{3}\right) = 1 \implies 3b + 2b + b = 1 \implies 6b = 1 \implies b = \frac{1}{6} \] Then, \[ a = 3b = \frac{1}{2}, \quad c = \frac{b}{3} = \frac{1}{18} \] ### Step 5: Calculate Maximum Value of \( E \) Now substituting \( a, b, c \) back into \( E \): \[ E = \left(\frac{1}{2}\right)^3 \left(\frac{1}{6}\right)^2 \left(\frac{1}{18}\right) = \frac{1}{8} \cdot \frac{1}{36} \cdot \frac{1}{18} = \frac{1}{5184} \] Thus, the maximum value of \( a^3 b^2 c \) is indeed \( \frac{1}{5184} \). ### Conclusion for Statement 1 Statement 1 is true. ### Step 6: Analyze Statement 2 The second statement claims that there exists an arithmetic progression such that the sum of its \( n \) terms is given by: \[ S_n = an^3 + bn^2 + cn + d \] ### Step 7: Determine Validity of Statement 2 The sum of the first \( n \) terms of an arithmetic progression is given by: \[ S_n = \frac{n}{2} (2a + (n-1)d) \] This is a linear function of \( n \), not a cubic polynomial. Therefore, Statement 2 is false. ### Final Answer - Statement 1 is true. - Statement 2 is false.
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