 Solution

ID: past-exam-of-the-mathematical-methods-ii-course-of-the-university-of-oxford/2013/10/a/solution

The terms

u_{tt}

and

c^{2} u_{xx}

must have the same dimensions. Likewise

a u

must match

u_{tt}

. Thus

[c] = length / time, [a] = time^{- 2} .

Only

c^{2}

∣ c ∣

when

c \neq = 0

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