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QJEEM24Ma6afd: JEE Main 2024 Mathematics - Class 11 JEEM24Ma6afd Solution: Let , be the roots of the equation . Let . Then is equal to

Let \alpha, \beta ; \alpha>\beta , be the roots of the equation x2−2x−3=0x^2-\sqrt{2} x-\sqrt{3}=0 . Let Pn=αn−βn,n∈N\mathrm{P}_n=\alpha^n-\beta^n, n \in \mathrm{N} . Then (113−102)P10+(112+10)P11−11P12(11 \sqrt{3}-10 \sqrt{2}) \mathrm{P}_{10}+(11 \sqrt{2}+10) \mathrm{P}_{11}-11 \mathrm{P}_{12} is equal to

Multiple Choice Options

  • A 103P910 \sqrt{3} \mathrm{P}_9
  • B 113P911 \sqrt{3} \mathrm{P}_9
  • C 112P911 \sqrt{2} \mathrm{P}_9
  • D 102P910 \sqrt{2} \mathrm{P}_9

Step-by-Step Verified Solution

amp;x2−2x−3=0amp;Pn=αn−βn\begin{aligned}& x^2-\sqrt{2} x-\sqrt{3}=0 \\& P_n=\alpha^n-\beta^n\end{aligned}

α\alpha and β\beta are the roots of the equation

Using Newton's theorem

amp;Pn+2−2Pn+1−3Pn=0amp; Put n=10amp;P12−2P11−3P10=0\begin{aligned}& P_{n+2}-\sqrt{2} P_{n+1}-\sqrt{3} P_n=0 \\& \text { Put } n=10 \\& P_{12}-\sqrt{2} P_{11}-\sqrt{3} P_{10}=0\end{aligned}

P12=2P11+3P10P_{12}=\sqrt{2} P_{11}+\sqrt{3} P_{10}

Put n=9n=9

amp;P11−2P10−3P9=0amp;P11=2P10+3P9amp;(113−102)P10+(112+10)P11−11P12\begin{aligned}& P_{11}-\sqrt{2} P_{10}-\sqrt{3} P_9=0 \\& P_{11}=\sqrt{2} P_{10}+\sqrt{3} P_9 \\& (11 \sqrt{3}-10 \sqrt{2}) P_{10}+(11 \sqrt{2}+10) P_{11}-11 P_{12}\end{aligned}

Put the value of P12P_{12} & P12P_{12} in above equation.

=amp;(113−102)P10+(112+10)(2P10+3P9)−11(2P11+3P10)=amp;113P10−102P10+22P10+102P10+116P9+103P9−112P11−113P10=amp;22P10+116P9+103P9−112(2P10+3P9)=amp;22P10+116P9+103P9−22P10−116P9=amp;103P9\begin{aligned}= & (11 \sqrt{3}-10 \sqrt{2}) P_{10}+(11 \sqrt{2}+10)\left(\sqrt{2} P_{10}+\sqrt{3} P_9\right)-11\left(\sqrt{2} P_{11}+\sqrt{3} P_{10}\right) \\= & 11 \sqrt{3} P_{10}-10 \sqrt{2} P_{10}+22 P_{10}+10 \sqrt{2} P_{10}+11 \sqrt{6} P_9+10 \sqrt{3} P_9-11 \sqrt{2} P_{11}-11 \sqrt{3} P_{10} \\= & 22 P_{10}+11 \sqrt{6} P_9+10 \sqrt{3} P_9-11 \sqrt{2}\left(\sqrt{2} P_{10}+\sqrt{3} P_9\right) \\= & 22 P_{10}+11 \sqrt{6} P_9+10 \sqrt{3} P_9-22 P_{10}-11 \sqrt{6} P_9 \\= & 10 \sqrt{3} P_9\end{aligned}

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