Question Bank • QB_EM_DE_007 NAT • 2 Marks

Section 1: Engineering Mathematics

Differential Equations

Subtopic: Higher order linear ODEs with constant coefficients

Question Statement:

Consider the differential equation $\frac{d^2 y}{dx^2} + 5\frac{dy}{dx} + 6y = 0$. The product of the two characteristic roots of this equation is ________ (answer in integer).

Answer Key:

6

Step-by-Step Solution & Explanation

The auxiliary equation is: $m^2 + 5m + 6 = 0$ Factoring the quadratic equation: $(m + 2)(m + 3) = 0$ The roots are $m_1 = -2$ and $m_2 = -3$. The product of the roots is: $m_1 \cdot m_2 = (-2) \times (-3) = 6$ (By Vieta's formulas, for $a m^2 + b m + c = 0$, the product of roots is $c/a = 6/1 = 6$).
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