Find the general solution of the differential equation d^2y/dx^2 - 5*dy/dx + 4y = 2x

Solve complimentary function: Let y = emx then,
d2y/dx2 - 5dy/dx + 4y = 0
m2emx - 5memx + 4emx = 0 (substituting for y)
emx(m2 - 5m + 4) = 0
emx(m - 4)(m - 1) = 0
Therefore m=4 and m=1, so the c.f. is y = Ae4x + Bex where A,B are constants

Solve particular integral: Let y = ax + b and substitute into the differential equation
0 - 5a + 4(ax + b) = 2x
4ax + (4b - 5a) = 2x
Therefore 4a=2 and 4b-5a=0 so a=1/2, b =5/8

Hence the general solution is y = c.f + p.i =  Ae4x + Bex + 1/2 x + 5/8

PM

Related Further Mathematics A Level answers

All answers ▸

Why is the integral of 1/sqrt(1-x^2)dx = sin^{-1}(x)?


Using graphs, show how the Taylor expansion can be used to approximate a trigonometric function.


Differentiate arctan of x with respect to x.


Find the set of values of x for which (x+4) > 2/(x+3)