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Which of the following is not true for equation `x^(2)log8-xlog5=2(log2)-x` (A) equation has one integral root (B) equation has no irrational roots (C) equation has rational roots (D) none of these

A

equation has one integral root

B

equation has no irrational roots

C

equation has rational roots

D

none of these

Text Solution

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The correct Answer is:
To solve the equation \( x^2 \log 8 - x \log 5 = 2 \log 2 - x \), we will first rearrange it into a standard quadratic form and analyze the roots. ### Step 1: Rearranging the Equation Start with the given equation: \[ x^2 \log 8 - x \log 5 = 2 \log 2 - x \] Rearranging gives: \[ x^2 \log 8 - x \log 5 + x - 2 \log 2 = 0 \] ### Step 2: Combine Like Terms We can factor out \( x \) from the terms involving \( x \): \[ x^2 \log 8 + x(1 - \log 5) - 2 \log 2 = 0 \] ### Step 3: Identify Coefficients This is a quadratic equation in the form \( ax^2 + bx + c = 0 \), where: - \( a = \log 8 \) - \( b = 1 - \log 5 \) - \( c = -2 \log 2 \) ### Step 4: Calculate the Discriminant The discriminant \( D \) of a quadratic equation \( ax^2 + bx + c = 0 \) is given by: \[ D = b^2 - 4ac \] Substituting the values: \[ D = (1 - \log 5)^2 - 4(\log 8)(-2 \log 2) \] ### Step 5: Simplify the Discriminant Calculate \( \log 8 \) and \( \log 2 \): \[ \log 8 = 3 \log 2 \] Thus, \[ D = (1 - \log 5)^2 + 8 (\log 2)^2 \] Since \( D \) is a sum of squares, \( D \geq 0 \). This means the equation has real roots. ### Step 6: Determine the Nature of Roots Since the discriminant is non-negative, the roots can be: - Two distinct real roots if \( D > 0 \) - One repeated real root if \( D = 0 \) ### Step 7: Check for Integral and Rational Roots To check if the roots are integral or rational, we can use the Rational Root Theorem. The potential rational roots are factors of \( -2 \log 2 \) divided by factors of \( \log 8 \). ### Step 8: Analyze the Options - **Option A**: "The equation has one integral root." We need to check if there is an integral root. - **Option B**: "The equation has no irrational roots." This is likely true since we have determined that the roots are rational. - **Option C**: "The equation has rational roots." This is likely true as well. - **Option D**: "None of these." This would be true if all previous options are true. ### Conclusion After analyzing the roots and their nature, we find that: - The equation does not have an integral root. - The equation has rational roots. Thus, the answer is **(A)**, as it is not true that the equation has one integral root.

To solve the equation \( x^2 \log 8 - x \log 5 = 2 \log 2 - x \), we will first rearrange it into a standard quadratic form and analyze the roots. ### Step 1: Rearranging the Equation Start with the given equation: \[ x^2 \log 8 - x \log 5 = 2 \log 2 - x \] Rearranging gives: ...
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