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Question: Answered & Verified by Expert
If $m$ and $n$ are order and degree of the equation $\left(\frac{d^{2} y}{d x^{2}}\right)^{5}+4 \cdot \frac{\left(\frac{d^{2} y}{d x^{2}}\right)^{3}}{\left(\frac{d^{3} y}{d x^{3}}\right)}+\left(\frac{d^{3} y}{d x^{3}}\right)=x^{2}-1$, then
MathematicsDifferential EquationsMHT CETMHT CET 2011
Options:
  • A $m=3, n=3$
  • B $m=3, n=2$
  • C $m=3, n=5$
  • D $m=3, n=1$
Solution:
2167 Upvotes Verified Answer
The correct answer is: $m=3, n=2$
The given differential equation can be rewritten as
$$
\begin{array}{l}
\left(\frac{d^{2} y}{d x^{2}}\right)^{5} \cdot \frac{d^{3} y}{d x^{3}}+4\left(\frac{d^{2} y}{d x^{2}}\right)^{3}+\left(\frac{d^{3} y}{d x^{3}}\right)^{2} \\
=\left(x^{2}-1\right) \frac{d^{3} y}{d x^{3}} \Rightarrow \text { order }(m)=3
\end{array}
$$
and $\quad$ degree $(n)=2$

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