Q:

Find the general solution of y"+4y=0.

Accepted Solution

A:
y = C1 cos (2x) + C2 sin (2x) where C1 and C2 are arbitrary constants. This can be found using the following steps: Find the characteristic equation of the differential equation. The characteristic equation is found by replacing y with e mx in the differential equation. This gives us the equation: m^2 + 4 = 0 Solve the characteristic equation for m. This gives us the following roots: m = -2, 2 Since the roots of the characteristic equation are complex, the general solution of the differential equation is of the form: y = C1 e^{-2x} + C2 e^{2x} We can use Euler's formula to convert the exponential terms into trigonometric terms. This gives us the following general solution: y = C1 cos (2x) + C2 sin (2x) where C1 and C2 are arbitrary constants. I hope this helps! Let me know if you have any other questions.