Question:medium

If \(5 - log_{10}\  \sqrt {1 + x }+ 4\  log_{10 }\  \sqrt {1-x} = log_{10}\  \frac {1}{\sqrt {1-x^2}}\), then \(100 x \) equals

Updated On: Jan 15, 2026
Show Solution

Solution and Explanation

The given equation is:

\[ 5 - \log_{10} \sqrt{1+x} + 4 \log_{10} \sqrt{1-x} = \log_{10} \frac{1}{\sqrt{1-x^2}} \]

Step 1: Equation Rearrangement

The right-hand side is rewritten as:

\[ 5 - \log_{10} \sqrt{1+x} + 4 \log_{10} \sqrt{1-x} = \log_{10} \left( \sqrt{1+x} \times \sqrt{1-x} \right)^{-1} \]

Step 2: Applying Logarithm Properties

Using the property \( \log_b(a^n) = n \log_b a \):

\[ 5 - \log_{10} \sqrt{1+x} + 4 \log_{10} \sqrt{1-x} = (-1) \log_{10} \left( \sqrt{1+x} \right) + (-1) \log_{10} \left( \sqrt{1-x} \right) \]

Step 3: Term Consolidation

The equation simplifies to:

\[ 5 = -\log_{10} \sqrt{1+x} + \log_{10} \sqrt{1+x} - \log_{10} \sqrt{1-x} - 4 \log_{10} \sqrt{1-x} \]

Step 4: Further Simplification

The equation reduces to:

\[ 5 = -5 \log_{10} \sqrt{1-x} \]

Step 5: Solving for \( x \)

Isolating \( \sqrt{1-x} \):

\[ \sqrt{1-x} = \frac{1}{10} \]

Squaring both sides yields:

\[ (\sqrt{1-x})^2 = \frac{1}{100} \]

This gives:

\[ 1 - x = \frac{1}{100} \]

Therefore:

\[ x = 1 - \frac{1}{100} = \frac{99}{100} \]

Step 6: Calculating the Final Result

The value of \( 100x \) is:

\[ 100x = 100 \times \frac{99}{100} = 99 \]

Conclusion:

The final answer is \( \boxed{99} \).

Was this answer helpful?
2


Questions Asked in CAT exam