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x and y are positive number.Let g and a ...

x and y are positive number.Let g and a be G.M. And AM of these numbers.Also let G be G.M of x + 1 and y + 1.If G and g are roots of equation `x^(2) - 5x + 6 = 0` , then

A

`x = 2, y = (3)/(4)`

B

`x = (3)/(4), y = 12`

C

`x = (5)/(2), y = (8)/(5)`

D

x = y = 2

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The correct Answer is:
To solve the problem step by step, we will follow the given information and derive the necessary equations. ### Step 1: Understand the Given Information We have two positive numbers \( x \) and \( y \). The geometric mean (G.M.) \( g \) and the arithmetic mean (A.M.) \( a \) of these numbers are defined as follows: - \( g = \sqrt{xy} \) - \( a = \frac{x + y}{2} \) We also have another G.M. \( G \) defined for \( x + 1 \) and \( y + 1 \): - \( G = \sqrt{(x + 1)(y + 1)} \) ### Step 2: Roots of the Quadratic Equation The roots of the equation \( x^2 - 5x + 6 = 0 \) can be found using the factorization method: \[ x^2 - 5x + 6 = (x - 2)(x - 3) = 0 \] Thus, the roots are \( x = 2 \) and \( x = 3 \). We can assign: - \( g = 2 \) - \( G = 3 \) ### Step 3: Set Up Equations From the definitions of \( g \) and \( G \), we can set up the following equations: 1. \( g = \sqrt{xy} = 2 \) 2. \( G = \sqrt{(x + 1)(y + 1)} = 3 \) ### Step 4: Solve for \( xy \) From the first equation: \[ \sqrt{xy} = 2 \implies xy = 2^2 = 4 \] ### Step 5: Solve for \( (x + 1)(y + 1) \) From the second equation: \[ \sqrt{(x + 1)(y + 1)} = 3 \implies (x + 1)(y + 1) = 3^2 = 9 \] Expanding this, we have: \[ xy + x + y + 1 = 9 \] Substituting \( xy = 4 \): \[ 4 + x + y + 1 = 9 \implies x + y + 5 = 9 \implies x + y = 4 \] ### Step 6: Solve the System of Equations Now we have a system of equations: 1. \( xy = 4 \) 2. \( x + y = 4 \) Let \( x \) and \( y \) be the roots of the quadratic equation \( t^2 - (x+y)t + xy = 0 \): \[ t^2 - 4t + 4 = 0 \] Factoring gives: \[ (t - 2)^2 = 0 \] Thus, \( t = 2 \) is a double root, meaning: \[ x = 2 \quad \text{and} \quad y = 2 \] ### Final Answer The values of \( x \) and \( y \) are both \( 2 \). ---
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