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Given that log₅ x = a and log₅ y = b, find log₅ (x²/25) in terms of a and b.

Mathematics

ScanSolve AI Answer

Answer

2a - 2

Step-by-step solution

5 steps

To find log⁡5(x225)\log_5 \left(\frac{x^2}{25}\right) in terms of aa and bb, we will use the properties of logarithms.

Given:
log⁡5x=a\log_5 x = a
log⁡5y=b\log_5 y = b

We need to simplify log⁡5(x225)\log_5 \left(\frac{x^2}{25}\right).

  1. Apply the quotient rule of logarithms, log⁡c(MN)=log⁡cM−log⁡cN\log_c \left(\frac{M}{N}\right) = \log_c M - \log_c N.

    log⁡5(x225)=log⁡5(x2)−log⁡5(25)\log_5 \left(\frac{x^2}{25}\right) = \log_5 (x^2) - \log_5 (25)
  2. Apply the power rule of logarithms, log⁡c(Mk)=klog⁡cM\log_c (M^k) = k \log_c M, to the first term.

    log⁡5(x2)=2log⁡5x\log_5 (x^2) = 2 \log_5 x

    Also, express 25 as a power of 5: 25=5225 = 5^2.

    log⁡5(25)=log⁡5(52)\log_5 (25) = \log_5 (5^2)
  3. Substitute these into the expression from Step 1.

    log⁡5(x225)=2log⁡5x−log⁡5(52)\log_5 \left(\frac{x^2}{25}\right) = 2 \log_5 x - \log_5 (5^2)
  4. Apply the power rule again to the second term and use the identity log⁡cc=1\log_c c = 1.

    log⁡5(52)=2log⁡55=2×1=2\log_5 (5^2) = 2 \log_5 5 = 2 \times 1 = 2
  5. Substitute the given value log⁡5x=a\log_5 x = a and the result from Step 4 into the expression.

    log⁡5(x225)=2a−2\log_5 \left(\frac{x^2}{25}\right) = 2a - 2

    The value bb is not used in this particular expression.

    The simplified expression is 2a−22a - 2.

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