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If log(10)|x^3 + y^3|-log(10) |x^2-xy + ...

If `log_(10)|x^3 + y^3|-log_(10) |x^2-xy + y^2|+log_(10)|x^3-y^3|-log_(10)|x^2+xy+y^2|=log_(10)221`. wherex, y are integers , then (i) if `x=111` then `y` can be: (ii) if `y=2`then value of `x` can be:

A

`pm 111`

B

`pm 2`

C

`pm 110`

D

`pm 109`

Text Solution

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The correct Answer is:
To solve the given logarithmic equation step by step, we start with the equation: \[ \log_{10}|x^3 + y^3| - \log_{10}|x^2 - xy + y^2| + \log_{10}|x^3 - y^3| - \log_{10}|x^2 + xy + y^2| = \log_{10}221 \] ### Step 1: Combine the logarithmic expressions using properties of logarithms Using the properties of logarithms, we can combine the terms: \[ \log_{10} \left( \frac{|x^3 + y^3| \cdot |x^3 - y^3|}{|x^2 - xy + y^2| \cdot |x^2 + xy + y^2|} \right) = \log_{10} 221 \] ### Step 2: Remove the logarithm by exponentiating both sides Since the logarithm is equal, we can exponentiate both sides to eliminate the logarithm: \[ \frac{|x^3 + y^3| \cdot |x^3 - y^3|}{|x^2 - xy + y^2| \cdot |x^2 + xy + y^2|} = 221 \] ### Step 3: Use the formulas for sums and differences of cubes Recall the formulas: - \( x^3 + y^3 = (x + y)(x^2 - xy + y^2) \) - \( x^3 - y^3 = (x - y)(x^2 + xy + y^2) \) Substituting these into our equation gives: \[ \frac{(x + y)(x^2 - xy + y^2) \cdot (x - y)(x^2 + xy + y^2)}{|x^2 - xy + y^2| \cdot |x^2 + xy + y^2|} = 221 \] ### Step 4: Simplify the equation The terms \( |x^2 - xy + y^2| \) and \( |x^2 + xy + y^2| \) cancel out, leading to: \[ |(x + y)(x - y)| = 221 \] ### Step 5: Solve for \( x \) and \( y \) This implies two cases: 1. \( (x + y)(x - y) = 221 \) 2. \( (x + y)(x - y) = -221 \) ### Step 6: Analyze the cases #### Case 1: \( (x + y)(x - y) = 221 \) Let \( a = x + y \) and \( b = x - y \). Then: \[ ab = 221 \] The integer factor pairs of 221 are \( (1, 221), (13, 17), (-1, -221), (-13, -17) \). From these pairs, we can find \( x \) and \( y \): 1. For \( (1, 221) \): - \( x + y = 221 \) - \( x - y = 1 \) - Solving gives \( x = 111, y = 110 \). 2. For \( (13, 17) \): - \( x + y = 17 \) - \( x - y = 13 \) - Solving gives \( x = 15, y = 2 \). 3. For \( (-1, -221) \): - \( x + y = -221 \) - \( x - y = -1 \) - Solving gives \( x = -111, y = -110 \). 4. For \( (-13, -17) \): - \( x + y = -17 \) - \( x - y = -13 \) - Solving gives \( x = -15, y = -2 \). #### Case 2: \( (x + y)(x - y) = -221 \) Similar factor pairs lead to: 1. For \( (1, -221) \): - \( x + y = -221 \) - \( x - y = 1 \) - Solving gives \( x = -110, y = -111 \). 2. For \( (13, -17) \): - \( x + y = -17 \) - \( x - y = 13 \) - Solving gives \( x = -2, y = -15 \). ### Step 7: Finding specific values (i) If \( x = 111 \): - From the first case, \( y \) can be \( 110 \) or \( -110 \). (ii) If \( y = 2 \): - From the second case, \( x \) can be \( 15 \) or \( -15 \). ### Final Answers: - (i) If \( x = 111 \), then \( y \) can be \( 110 \) or \( -110 \). - (ii) If \( y = 2 \), then \( x \) can be \( 15 \) or \( -15 \).
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