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The sum of solution of the equation log(...

The sum of solution of the equation `log_(10)(3x^(2) +12x +19) - log_(10)(3x +4) = 1` is

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To solve the equation \( \log_{10}(3x^2 + 12x + 19) - \log_{10}(3x + 4) = 1 \), we will follow these steps: ### Step 1: Apply the properties of logarithms Using the property of logarithms that states \( \log_a(b) - \log_a(c) = \log_a\left(\frac{b}{c}\right) \), we can rewrite the equation: \[ \log_{10}\left(\frac{3x^2 + 12x + 19}{3x + 4}\right) = 1 \] ### Step 2: Eliminate the logarithm To eliminate the logarithm, we exponentiate both sides with base 10: \[ \frac{3x^2 + 12x + 19}{3x + 4} = 10 \] ### Step 3: Multiply both sides by \(3x + 4\) To eliminate the fraction, multiply both sides by \(3x + 4\): \[ 3x^2 + 12x + 19 = 10(3x + 4) \] ### Step 4: Expand the right side Expanding the right side gives: \[ 3x^2 + 12x + 19 = 30x + 40 \] ### Step 5: Rearrange the equation Rearranging the equation to bring all terms to one side results in: \[ 3x^2 + 12x + 19 - 30x - 40 = 0 \] This simplifies to: \[ 3x^2 - 18x - 21 = 0 \] ### Step 6: Divide the entire equation by 3 To simplify, divide the entire equation by 3: \[ x^2 - 6x - 7 = 0 \] ### Step 7: Factor the quadratic equation Now, we will factor the quadratic equation: \[ (x - 7)(x + 1) = 0 \] ### Step 8: Solve for \(x\) Setting each factor to zero gives us the solutions: 1. \(x - 7 = 0 \implies x = 7\) 2. \(x + 1 = 0 \implies x = -1\) ### Step 9: Check the validity of the solutions We need to ensure that both solutions satisfy the original logarithmic conditions (the arguments must be positive): - For \(x = 7\): - \(3(7)^2 + 12(7) + 19 = 147 + 84 + 19 = 250\) (positive) - \(3(7) + 4 = 21 + 4 = 25\) (positive) - For \(x = -1\): - \(3(-1)^2 + 12(-1) + 19 = 3 - 12 + 19 = 10\) (positive) - \(3(-1) + 4 = -3 + 4 = 1\) (positive) Both solutions are valid. ### Step 10: Find the sum of the solutions The sum of the solutions is: \[ 7 + (-1) = 6 \] ### Final Answer The sum of the solutions of the equation is \( \boxed{6} \). ---
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