NIMCET 2025 — Mathematics PYQ
NIMCET | Mathematics | 2025If 8x−1=(41)x, then find the value of:logx+14−logx+151+log1−x4−log1−x51
Choose the correct answer:
- A.
5/4
- B.
1
- C.
2
(Correct Answer) - D.
4/5
2
Explanation
The solution to this problem is broken down into two main parts: finding the value of x from the exponential equation, and then substituting that value to simplify the logarithmic expression.
Step 1: Solve for x from the Exponential EquationWe are given:8x−1=(41)xExpress both sides using a common base of 2:8 = 2^3 \implies 8^{x-1} = (2^3)^{x-1} = 2^{3x-3}<span class="katex-error" title="ParseError: KaTeX parse error: Can't use function '' in math mode at position 102: …2})^x = 2^{-2x}̲Equating the po…" style="color:#cc0000">\frac{1}{4} = 4^{-1} = (2^2)^{-1} = 2^{-2} \implies \left(\frac{1}{4}\right)^x = (2^{-2})^x = 2^{-2x}Equating the powers: 2^{3x-3} = 2^{-2x} Sincethebasesareidentical,theirexponentsmustbeequal: 3x - 3 = -2x 3x + 2x = 3 5x = 3 x = \frac{3}{5} = 0.6 ' in math mode at position 54: …Now substitute̲x = \frac{3}{5}…" style="color:#cc0000">Step 2: Simplify the Logarithmic BasesNow substitute x=53 into the bases of the given expression:First base: x+1=53+1=58Second base: 1−x=1−53=52Step 3: Simplify the Logarithmic ExpressionLet the given expression be denoted as E: E = \frac{1}{\log_{\frac{8}{5}}4 - \log_{\frac{8}{5}}5} + \frac{1}{\log_{\frac{2}{5}}4 - \log_{\frac{2}{5}}5} ' in math mode at position 44: …of logarithms,̲\log_b a - \log…" style="color:#cc0000">Using the quotient property of logarithms, logba−logbc=logb(ca): E = \frac{1}{\log_{\frac{8}{5}}\left(\frac{4}{5}\right)} + \frac{1}{\log_{\frac{2}{5}}\left(\frac{4}{5}\right)} ' in math mode at position 61: …hing property,̲\frac{1}{\log_b…" style="color:#cc0000">Using the change of base formula / base-switching property, logba1=logab: E = \log_{\frac{4}{5}}\left(\frac{8}{5}\right) + \log_{\frac{4}{5}}\left(\frac{2}{5}\right) ' in math mode at position 43: …of logarithms,̲\log_b m + \log…" style="color:#cc0000">Using the product property of logarithms, logbm+logbn=logb(m⋅n): E = \log_{\frac{4}{5}}\left(\frac{8}{5} \times \frac{2}{5}\right) E = \log_{\frac{4}{5}}\left(\frac{16}{25}\right) ' in math mode at position 13: Notice that̲\frac{16}{25}…" style="color:#cc0000">Notice that\frac{16}{25}isthesquareof\frac{4}{5}:</span> \frac{16}{25} = \left(\frac{4}{5}\right)^2 <span class="katex-display"><span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mord mathnormal" style="margin-right:0.0576em;">S</span><span class="mord mathnormal">u</span><span class="mord mathnormal">b</span><span class="mord mathnormal">s</span><span class="mord mathnormal">t</span><span class="mord mathnormal">i</span><span class="mord mathnormal">t</span><span class="mord mathnormal">u</span><span class="mord mathnormal">t</span><span class="mord mathnormal">e</span><span class="mord mathnormal">t</span><span class="mord mathnormal">hi</span><span class="mord mathnormal">s</span><span class="mord mathnormal">ba</span><span class="mord mathnormal">c</span><span class="mord mathnormal" style="margin-right:0.0315em;">k</span><span class="mord mathnormal">in</span><span class="mord mathnormal">t</span><span class="mord mathnormal">o</span><span class="mord mathnormal">t</span><span class="mord mathnormal">h</span><span class="mord mathnormal">ee</span><span class="mord mathnormal">x</span><span class="mord mathnormal">p</span><span class="mord mathnormal" style="margin-right:0.0278em;">r</span><span class="mord mathnormal">ess</span><span class="mord mathnormal">i</span><span class="mord mathnormal">o</span><span class="mord mathnormal">n</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">:</span></span></span></span></span> E = \log_{\frac{4}{5}}\left(\frac{4}{5}\right)^2 <span class="katex-display"><span class="katex"><span class="katex-html" aria-hidden="true"></span></span></span> E = 2 \log_{\frac{4}{5}}\left(\frac{4}{5}\right) <span class="katex-error" title="ParseError: KaTeX parse error: Can't use function '' in math mode at position 7: Since ̲\log_b b = 1:" style="color:#cc0000">Since logbb=1: E = 2 \times 1 = 2 $$
Explanation
The solution to this problem is broken down into two main parts: finding the value of x from the exponential equation, and then substituting that value to simplify the logarithmic expression.
Step 1: Solve for x from the Exponential EquationWe are given:8x−1=(41)xExpress both sides using a common base of 2:8 = 2^3 \implies 8^{x-1} = (2^3)^{x-1} = 2^{3x-3}<span class="katex-error" title="ParseError: KaTeX parse error: Can't use function '' in math mode at position 102: …2})^x = 2^{-2x}̲Equating the po…" style="color:#cc0000">\frac{1}{4} = 4^{-1} = (2^2)^{-1} = 2^{-2} \implies \left(\frac{1}{4}\right)^x = (2^{-2})^x = 2^{-2x}Equating the powers: 2^{3x-3} = 2^{-2x} Sincethebasesareidentical,theirexponentsmustbeequal: 3x - 3 = -2x 3x + 2x = 3 5x = 3 x = \frac{3}{5} = 0.6 ' in math mode at position 54: …Now substitute̲x = \frac{3}{5}…" style="color:#cc0000">Step 2: Simplify the Logarithmic BasesNow substitute x=53 into the bases of the given expression:First base: x+1=53+1=58Second base: 1−x=1−53=52Step 3: Simplify the Logarithmic ExpressionLet the given expression be denoted as E: E = \frac{1}{\log_{\frac{8}{5}}4 - \log_{\frac{8}{5}}5} + \frac{1}{\log_{\frac{2}{5}}4 - \log_{\frac{2}{5}}5} ' in math mode at position 44: …of logarithms,̲\log_b a - \log…" style="color:#cc0000">Using the quotient property of logarithms, logba−logbc=logb(ca): E = \frac{1}{\log_{\frac{8}{5}}\left(\frac{4}{5}\right)} + \frac{1}{\log_{\frac{2}{5}}\left(\frac{4}{5}\right)} ' in math mode at position 61: …hing property,̲\frac{1}{\log_b…" style="color:#cc0000">Using the change of base formula / base-switching property, logba1=logab: E = \log_{\frac{4}{5}}\left(\frac{8}{5}\right) + \log_{\frac{4}{5}}\left(\frac{2}{5}\right) ' in math mode at position 43: …of logarithms,̲\log_b m + \log…" style="color:#cc0000">Using the product property of logarithms, logbm+logbn=logb(m⋅n): E = \log_{\frac{4}{5}}\left(\frac{8}{5} \times \frac{2}{5}\right) E = \log_{\frac{4}{5}}\left(\frac{16}{25}\right) ' in math mode at position 13: Notice that̲\frac{16}{25}…" style="color:#cc0000">Notice that\frac{16}{25}isthesquareof\frac{4}{5}:</span> \frac{16}{25} = \left(\frac{4}{5}\right)^2 <span class="katex-display"><span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mord mathnormal" style="margin-right:0.0576em;">S</span><span class="mord mathnormal">u</span><span class="mord mathnormal">b</span><span class="mord mathnormal">s</span><span class="mord mathnormal">t</span><span class="mord mathnormal">i</span><span class="mord mathnormal">t</span><span class="mord mathnormal">u</span><span class="mord mathnormal">t</span><span class="mord mathnormal">e</span><span class="mord mathnormal">t</span><span class="mord mathnormal">hi</span><span class="mord mathnormal">s</span><span class="mord mathnormal">ba</span><span class="mord mathnormal">c</span><span class="mord mathnormal" style="margin-right:0.0315em;">k</span><span class="mord mathnormal">in</span><span class="mord mathnormal">t</span><span class="mord mathnormal">o</span><span class="mord mathnormal">t</span><span class="mord mathnormal">h</span><span class="mord mathnormal">ee</span><span class="mord mathnormal">x</span><span class="mord mathnormal">p</span><span class="mord mathnormal" style="margin-right:0.0278em;">r</span><span class="mord mathnormal">ess</span><span class="mord mathnormal">i</span><span class="mord mathnormal">o</span><span class="mord mathnormal">n</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">:</span></span></span></span></span> E = \log_{\frac{4}{5}}\left(\frac{4}{5}\right)^2 <span class="katex-display"><span class="katex"><span class="katex-html" aria-hidden="true"></span></span></span> E = 2 \log_{\frac{4}{5}}\left(\frac{4}{5}\right) <span class="katex-error" title="ParseError: KaTeX parse error: Can't use function '' in math mode at position 7: Since ̲\log_b b = 1:" style="color:#cc0000">Since logbb=1: E = 2 \times 1 = 2 $$

