Further Maths - Coupled Differential Equations

2021-09-10
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2021-09-10

What is the general process for solving a coupled first-order differential equation??

Eliminating one of the variables to form a single second-order differential equation.

$$\frac{\text{d}x}{\text{d}t} = x + y \\ \frac{\text{d}y}{\text{d}t} = x - y$$ What are the 3 first steps??

Rewriting it as $y = …$, differentiating and then substituting.

$$\frac{\text{d}x}{\text{d}t} = x + y \\ \frac{\text{d}y}{\text{d}t} = x - y$$ You’ve discovered $$x = Ae^{\sqrt{2}t} + Be^{-\sqrt{2}t}$$ What do you now do to find $y$ in terms of $t$??

Differentiate $x$ and then substitute both back into the original differential equation for $\frac{\text{d}x}{\text{d}t}$.

When is a coupled first-order differential equation “homogenous”??

If there are no extra $f(t)$ or $g(t)$ in either of the definitions.


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date: 2021-09-10 17:22
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title: Further Maths - Coupled Differential Equations