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Assuming[{a >= 0, b >= 0, c >= 0, d >= 0, A >= 0, x[t] >= 0,
y[t] >= 0, z[t] >= 0, x[t] + y[t] + z[t] == A},
DSolve[{y'[t] == -a*y[t] + b*x[t],
x'[t] == a*y[t] - b*x[t] + c*z[t] - d*x[t],
z'[t] == -c*z[t] + d*x[t], y[0] == 0, z[0] == 0, x[0] == A}, {x, y,
z}, t]]
楼主运行该命令试试,应该是可以的。 |
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