Question:

If y=e⁻ˣ x and y+k y'=0, where y₄=d⁴ydx⁴, then k=

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Use characteristic equation for exponential–trigonometric functions.
Updated On: Mar 17, 2026
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The Correct Option is D

Solution and Explanation

Given y=e⁻ˣ x. Characteristic equation: (D+1)²+1=0 D²+2D+2=0 Thus the differential equation is: y''+2y'+2y=0 Differentiating twice more: y⁽⁴⁾+2y⁽³⁾+2y''=0 y⁽⁴⁾=-2y⁽³⁾-2y'' Comparing with y₄+ky=0, we get: k=-2
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