MATLAB解2次方程组

来源：百度知道 编辑：UC知道 时间：2024/06/23 18:08:27
0.00395P-1.222114
= -0.00000918M²+0.00632484M-0.94753494
= -0.000935085N+0.1344312847N
P+M+N=60
解出P,M,N.我还需要MATLAB程序，帮忙的谢谢了~！

需要观察方程的结构啊：

clc;clear
P=solve('0.00395*P-1.222114= -0.00000918*M^2+0.00632484*M-0.94753494','P')
N=solve('0.00395*P-1.222114= -0.000935085*N+0.1344312847*N','N')
f=sym('P+M+N-60')
f=subs(f)
M=solve(f)
P=subs(P);
P=eval(P)
N=subs(N,'P',P)

结果：
P =

69.513686075949367088607594936709-.23240506329113924050632911392405e-2*M^2+1.6012253164556962025316455696203*M

N =

.29588857277410571860646007588185e-1*P-9.1546725880317325617472240297789

f =

P+M+N-60

f =

2.415844024045622895356227047770-.23928166353940833037166405948505e-2*M^2+2.6486037438132803750195160239580*M

M =

-.91136946017033357359515757682753
1107.8092840916733814218366903122

P =

-0.91137
1107.8
-0.91137
1107.8

N =

-9.1