# Question:How to solve Laplace transformations of systems of differential equations

## Question:How to solve Laplace transformations of systems of differential equations

Maple 2016

My question is: Use the laplace transform to solve the system.

dx/dt + d^2y/dt^2 = 5e^(2t)

dx/dt - x - dy/dt + y = 8e^(2t)

x(0) = 2, y(0) = 1, y'(0) = 1

What I've done in Maple:

with(inttrans);
with(DEtools);
eq5 := (diff(x(t), t)+diff(y(t), t\$2) = 5*exp(2*t), t, s);

eq5s := laplace(%, t, s);

eq6 := (diff(x(t), t)-x-(diff(y(t), t))+y = 8*exp(2*t), t, s);

eq6s := laplace(%, t, s);

solve({eq5s, eq6s}, {laplace(x(t), t, s), laplace(y(t), t, s)});

subs({x(0) = 2, y(0) = 1, (D(y))(0) = 1}, %);

eq3 := invlaplace(%, s, t);

How do I simplify?  If you plug it into maple I come up with an answer that has x and y on each side.  I guess I'm just wondering how I can set them equal to each other to solve and get rid of the variable x and y.  I know answer is correct as I've also ran it through ODEtest.  Please help.

However you figure out getting rid of the variables I assume will help me also in solving the next problem:

Use the Laplace Transform to solve the system

dx/dt = 7x - y + 6z

dy/dt = -10x + 4y - 12z

dz/dt = -2x + y - z

x(0) = 5, y(0) = 7, z(0) = 2

I have attempted the second problem much like the first.  Thank you for your time.

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