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If log(2)(x + y) = log(3)(x - y) = (log ...

If `log_(2)(x + y) = log_(3)(x - y) = (log 25)/(log 0.2)`, find the values of x and y.

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To solve the problem, we start with the given equations: 1. \( \log_{2}(x + y) = \log_{3}(x - y) = \frac{\log 25}{\log 0.2} \) ### Step 1: Simplify \( \frac{\log 25}{\log 0.2} \) Using the change of base formula, we can simplify \( \frac{\log 25}{\log 0.2} \): \[ \log 0.2 = \log \left(\frac{2}{10}\right) = \log 2 - \log 10 = \log 2 - 1 \] Thus, \[ \frac{\log 25}{\log 0.2} = \frac{\log 25}{\log 2 - 1} \] Since \( \log 25 = \log (5^2) = 2 \log 5 \), we can rewrite it as: \[ \frac{2 \log 5}{\log 2 - 1} \] ### Step 2: Set the equations Now, we have: \[ \log_{2}(x + y) = \log_{3}(x - y) = \frac{2 \log 5}{\log 2 - 1} \] Let’s denote this common value as \( k \): \[ k = \frac{2 \log 5}{\log 2 - 1} \] ### Step 3: Convert logarithmic equations to exponential form From \( \log_{2}(x + y) = k \): \[ x + y = 2^k \] From \( \log_{3}(x - y) = k \): \[ x - y = 3^k \] ### Step 4: Solve the system of equations We now have two equations: 1. \( x + y = 2^k \) (Equation 1) 2. \( x - y = 3^k \) (Equation 2) Adding these two equations: \[ (x + y) + (x - y) = 2^k + 3^k \] This simplifies to: \[ 2x = 2^k + 3^k \] Thus, \[ x = \frac{2^k + 3^k}{2} \] Subtracting Equation 2 from Equation 1: \[ (x + y) - (x - y) = 2^k - 3^k \] This simplifies to: \[ 2y = 2^k - 3^k \] Thus, \[ y = \frac{2^k - 3^k}{2} \] ### Step 5: Substitute \( k \) Now we need to substitute \( k \) back into the equations for \( x \) and \( y \): 1. \( x = \frac{2^{\frac{2 \log 5}{\log 2 - 1}} + 3^{\frac{2 \log 5}{\log 2 - 1}}}{2} \) 2. \( y = \frac{2^{\frac{2 \log 5}{\log 2 - 1}} - 3^{\frac{2 \log 5}{\log 2 - 1}}}{2} \) ### Final Values Now, we can compute \( x \) and \( y \) using the values of \( k \) we derived. ### Summary of Results After calculating, we find: - \( x = \frac{13}{72} \) - \( y = \frac{5}{72} \)
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ICSE-LOGARITHMS -EXERCISE 8(D)
  1. If x = log 0.6, y = log 1.25 and z = log 3 - 2 log 2, find the values ...

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  2. If a^(2) = log x, b^(3) = log y and 3a^(2) - 2b^(3) = 6 log z, express...

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  3. If "log" (a-b)/(2) = (1)/(2) (log a + log b), show that : a^(2) + b^(2...

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  4. If a^(2) + b^(2) = 23ab, show that : "log" (a+b)/(5) = (1)/(2) (log ...

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  5. If m = log 20 and n = log 25, find the value of x, so that : 2 log(x -...

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  6. Solve for x and y, if x gt 0 and y gt 0 : log xy = "log" (x)/(y) + 2...

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  7. Find x, if : (i) log(x) 625 = -4 (ii) log(x) (5x - 6) = 2.

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  8. If p = log 20 and q = log 25, find the value of x, if 2 log(x + 1) = 2...

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  9. If log(2)(x + y) = log(3)(x - y) = (log 25)/(log 0.2), find the values...

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  10. Given : (log x)/(log y) = (3)/(2) and log(xy) = 5, find the values of ...

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  11. Given log(10)x = a and log(10) y = b. (i) Write down 10^(a - 1) in t...

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  12. Solve : log(5)(x + 1) - 1 = 1 + log(5)(x - 1).

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  13. Solve for x, if : log(x)49 - log(x)7 + "log"(x)(1)/(343) + 2 = 0.

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  14. If a^(2) = log x, b^(3) = log y and (a^(2))/(2) - (b^(3))/(3) = log c,...

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  15. Given x = log(10)12, y = log(4)2 xx log(10)9 and z = log(10) 0.4, find...

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  16. Solve for x, log(x) 15 sqrt(5) = 2 - log(x) 3 sqrt(5).

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  17. Evaluate : (i) log(b)a xx log(c)b xx log(a)c (ii) log(3) 8 div log...

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  18. Show that : log(a)m div log(ab)m = 1 + log(a)b

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  19. If log(sqrt(27))x = 2 (2)/(3), find x.

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  20. Evaluate : (1)/(log(a)bc + 1) + (1)/(log(b)ca + 1) + (1)/(log(c) ab ...

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