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The degree of the differential equation (2+(dydx)2)32=a2d2ydx2\left(2 + \left(\frac{dy}{dx}\right)^2\right)^{\frac{3}{2}} = a^2 \frac{d^2y}{dx^2} is:

Solution

Correct Option: 4

The degree of a differential equation is the highest power of the highest order derivative when the equation is in polynomial form (no roots, no fractions with derivatives).

Given equation:

(2+(dydx)2)32=a2d2ydx2\left(2 + \left(\frac{dy}{dx}\right)^2\right)^{\frac{3}{2}} = a^2 \frac{d^2y}{dx^2}


The highest order derivative in the equation is d2ydx2\frac{d^2y}{dx^2} (second order).

The left side has a fractional power 32\frac{3}{2}, so the equation is not in polynomial form.


Squaring both sides:

[(2+(dydx)2)32]2=[a2d2ydx2]2\left[\left(2 + \left(\frac{dy}{dx}\right)^2\right)^{\frac{3}{2}}\right]^{2} = \left[a^2 \frac{d^2y}{dx^2}\right]^{2}

(2+(dydx)2)3=a4(d2ydx2)2\left(2 + \left(\frac{dy}{dx}\right)^2\right)^3 = a^4 \left(\frac{d^2y}{dx^2}\right)^{2}


The equation is now in polynomial form.

The highest order derivative d2ydx2\frac{d^2y}{dx^2} appears with power 22.

Therefore, the degree of the differential equation is 22.

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