用LINGO解最优化问题中程序没有最优解帮看看要怎么改

Question

min=7.2*x1+7.2*x3+7.2*x4+7.2*x5+(x3+x4+x5)*21.4834;
x1^2=15^2+(5-x5-(x3^2-n^2)^0.5)^2;
(5-n)^2+(8-x5)^2=x4^2;
n<5;

Answer 1

有解啊：
Global optimal solution found.
Objective value: 384.4406
Extended solver steps: 16
Total solver iterations: 5426

Variable Value Reduced Cost
X1 15.81139 0.000000
X3 0.000000 0.000000
X4 9.433981 0.000000
X5 0.000000 0.000000
N 0.7071068E-07 0.000000

Answer 2

384.4406