If $\mathrm{m}$ is order and $\mathrm{n}$ is degree of the differential equation…

If $\mathrm{m}$ is order and $\mathrm{n}$ is degree of the differential equation $\mathrm{y}=\frac{\mathrm{dp}}{\mathrm{dx}}+\sqrt{\mathrm{a}^2 \mathrm{p}^2-\mathrm{b}^2}$, where $\mathrm{p}=\frac{\mathrm{dp}}{\mathrm{dx}}$, then the value of $\mathrm{m}+\mathrm{n}$ is
  1. 2
  2. 3
  3. 4
  4. 5

Solution

$\begin{aligned} & y=\frac{d p}{d x}+\sqrt{a^2 p^2-b^2}=\frac{d}{d x}\left(\frac{d y}{d x}\right)+\sqrt{a^2\left(\frac{d y}{d x}\right)^2-b^2} \\ & \therefore y-\frac{d^2 y}{d x^2}=\sqrt{a^2\left(\frac{d y}{d x}\right)^2-b^2} \end{aligned}$ Squaring both sides, we write $\begin{aligned} & y^2+\left(\frac{d^2 y}{d x}\right)^2-2 y \frac{d^2 y}{d x^2}=a^2\left(\frac{d y}{d x}\right)^2-b^2 \\ & \therefore \text { order }=2 \text { and degree }=2 \end{aligned}$

Asked in: MHT CET 2021 (20 Sep Shift 2)

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