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
AI Generated Solution
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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