Finding the Laplace transform (using the Table of Laplace Transforms) of each differential equation yields:

First equation: MATH

MATH

MATH

MATH...(1)

Second equation: MATH

$X-(sY-y(0))-Y=0$

$X-sY+3-Y=0$

MATH...(2)

We now have 2 equations in 3 unknowns (X, Y and s). We need to solve for X and Y and leave s on the right hand side of each expression. We choose to solve for Y first.

(2) × (s + 1):

...(3)

(1) − (3) gives:

MATH


MATH

The last step above is using partial fractions.


MATH

s2 terms: A + B = 3

s terms: 2A + C = 7

Constant terms: 5A = 10

So MATH

We can now write Y as the sum of partial fractions:

MATH

Finding the inverse Laplace of our expression for Y gives:

MATH


We now need to find the expression for x. Equation (2) gives us:

$X=-3+(s+1)Y$

and since MATH, we have:


MATH

MATH

So MATH

Therefore,

MATH