Example

Try It 10.39: Solving logx64=2\log_x 64 = 2, log5x=3\log_5 x = 3, and log1214=x\log_{\frac{1}{2}} \frac{1}{4} = x

To find the value of xx in the logarithmic equations logx64=2\log_x 64 = 2, log5x=3\log_5 x = 3, and log1214=x\log_{\frac{1}{2}} \frac{1}{4} = x, convert each equation into its equivalent exponential form. For logx64=2\log_x 64 = 2, the exponential equation is x2=64x^2 = 64. Solving this quadratic equation yields x=8x = 8 or x=8x = -8. Since the base of a logarithmic function must be positive, x=8x = -8 is eliminated, leaving x=8x = 8. For log5x=3\log_5 x = 3, the exponential form is 53=x5^3 = x, which simplifies to x=125x = 125. For log1214=x\log_{\frac{1}{2}} \frac{1}{4} = x, the exponential equation is \left(\frac{1}{2} ight)^x = \frac{1}{4}. By rewriting 14\frac{1}{4} as a power of 12\frac{1}{2}, the equation becomes \left(\frac{1}{2} ight)^x = \left(\frac{1}{2} ight)^2. Since the bases are identical, the exponents must be equal, giving x=2x = 2.

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Updated 2026-05-25

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