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1 It log(3)x+log(3)y=2+log(3)2 and log(3...

1 It `log_(3)x+log_(3)y=2+log_(3)2` and `log_(3)(x+y)=2` Then

A

`x=1`, `y=8`

B

`x=9`, `y=3`

C

`x=3`, `y=6`

D

none of these

Text Solution

AI Generated Solution

The correct Answer is:
To solve the equations given in the problem, we will follow these steps: ### Step 1: Rewrite the first equation We start with the equation: \[ \log_3 x + \log_3 y = 2 + \log_3 2 \] Using the property of logarithms that states \(\log_a b + \log_a c = \log_a (bc)\), we can combine the left side: \[ \log_3 (xy) = 2 + \log_3 2 \] ### Step 2: Simplify the right side We can rewrite the right side using the property of logarithms: \[ 2 + \log_3 2 = \log_3 (3^2) + \log_3 2 = \log_3 (9 \cdot 2) = \log_3 18 \] Thus, we have: \[ \log_3 (xy) = \log_3 18 \] ### Step 3: Equate the arguments of the logarithms Since the logarithms are equal, we can equate the arguments: \[ xy = 18 \] ### Step 4: Use the second equation Now we consider the second equation: \[ \log_3 (x + y) = 2 \] This implies: \[ x + y = 3^2 = 9 \] ### Step 5: Solve the system of equations Now we have a system of two equations: 1. \(xy = 18\) 2. \(x + y = 9\) We can solve for \(x\) and \(y\) using these equations. Let's express \(y\) in terms of \(x\) from the second equation: \[ y = 9 - x \] Substituting this into the first equation: \[ x(9 - x) = 18 \] Expanding this gives: \[ 9x - x^2 = 18 \] Rearranging leads to: \[ x^2 - 9x + 18 = 0 \] ### Step 6: Solve the quadratic equation We can solve this quadratic equation using the quadratic formula: \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] where \(a = 1\), \(b = -9\), and \(c = 18\): \[ x = \frac{9 \pm \sqrt{(-9)^2 - 4 \cdot 1 \cdot 18}}{2 \cdot 1} \] Calculating the discriminant: \[ x = \frac{9 \pm \sqrt{81 - 72}}{2} = \frac{9 \pm \sqrt{9}}{2} = \frac{9 \pm 3}{2} \] This gives us two potential solutions: \[ x = \frac{12}{2} = 6 \quad \text{and} \quad x = \frac{6}{2} = 3 \] ### Step 7: Find corresponding values of \(y\) Using \(x + y = 9\): - If \(x = 6\), then \(y = 9 - 6 = 3\). - If \(x = 3\), then \(y = 9 - 3 = 6\). Thus, the solutions are: \[ (x, y) = (6, 3) \quad \text{or} \quad (3, 6) \] ### Final Answer The values of \(x\) and \(y\) are \(3\) and \(6\). ---
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