472
solve Symbolic Math Toolbox. , , .
1
Syms a b c x;
f=a*x^2+b*x+c
Solve(f)
>> syms a b c x;
f=a*x^2+b*x+c
solve(f)
f =
a*x^2 + b*x + c
ans =
-(b + (b^2 - 4*a*c)^(1/2))/(2*a)
-(b - (b^2 - 4*a*c)^(1/2))/(2*a)
>>
solve('x^2-5*x+6=0',x)
>> solve('x^2-5*x+6=0',x)
ans =
:
S=solve('x^2-5*x+6=0',x)
2
syms x; %
S=solve('x^3-9*x^2+26*x-24=0',x)
>> S=solve('x^3-9*x^2+26*x-24=0',x)
S =
2
2.1
syms x y; %
solve('x+y=3','x*y^2=4',x,y)%
% S: ;
S=solve('x+y=3','x*y^2=4',x,y)%
S.x % x: (x1=1; x2=4)
S.y % y: (y1=2; y2=-1)
% ans=
%:(1; 2) (4; -1)
Pause
2.2
syms x y;
t=solve('2*x+5*y=26','3*x-y=5',x,y)
t.x
t.y
% , =0
disp(' 2 , ')
syms x y;
t=solve('2*x+5*y-26','3*x-y-5',x,y)% ,
% .
% x y ( t.x t.y)
X=t.x % X Y
Y=t.y
3
1).
syms x y z;
d=solve('0.1*x-0.04*y-0.13*z=-0.15','-0.04*x-0.34*y+0.05*z=0.31','-0.13*x+0.05*y+0.63*x=0.37',x,y,z);
R=[d.x;d.y;d.z] % x,y,z.
%: R = 0.81135 -0.71347 1.9975
disp(vpa(R,3))
%
R=vpa(R,3) % 3 ( + -)
2).
syms x y z;
d=solve('2*abs(x*y-3*y-4*x+12)+z=-23.16','z=-24.08','z-(x^2)-(y^2)+6*x+8*y=0',x,y,z)
dxyz=[d.x;d.y;d.z] %
XYZ=vpa(dxyz,3)% = 3
%( + -)
%: x=2.32; y=3.32; z=-24.1
4
y=x^3-1
syms x y; %
solve(x^3-1,x)
ans =
- 1/2 - (3^(1/2)*i)/2
- 1/2 + (3^(1/2)*i)/2
solve('x^3-1=0',x)
5
solve('x^2-5*x+6=0',x) %: 2 3
ans =
6
|
|
|
S=solve('x+y=3','x*y^2=4',x,y) %;
(2 ),
% S.x S.y x y.
S.x
S.y
>> S=solve('x+y=3','x*y^2=4',x,y)
S =
x: [2x1 sym]
y: [2x1 sym]
>> S.x
S.y
ans =
ans =
-1
% (1;2)(4;-1)
7
solve('2^x=8',x) %: 3
8
0.25*x + sin(x) -1=0
solve('0.25*x + sin(x) -1)
ans =
0.89048708074438001001103173059554
_______________________________________________________
4.
2
disp(' -2 3 ')
A=[2 3 -2;5 -2 4;3 -1 2]
B=[11;8;5]
x1=A\B
x2=A^(-1)*B
x3=inv(A)*B
A*x1 %
Syms x y z;
d=solve('0.1*x-0.04*y-0.13*z=-0.15','-0.04*x-0.34*y+0.05*z=0.31','-0.13*x+0.05*y+0.63*x=0.37',x,y,z);
R=[d.x;d.y;d.z] % x,y,z.
%: R = 0.81135 -0.71347 1.9975
Disp(vpa(R,3))
%
R=vpa(R,3) % 3 ( + -)
A=[1 2 3 4;-1 2 -3 4;0 1 -1 1;1 1 1 1]
b=[30;10;3;10]
Rank(A)
A1=A; A2=A; A3=A; A4=A;
A1(:,1)=b;
A2(:,2)=b;
A3(:,3)=b;
A4(:,4)=b;
x1=det(A1)/det(A)
x2=det(A2)/det(A)
x3=det(A3)/det(A)
x4=det(A4)/det(A)
x=[x1;x2;x3;x4];
A*x %
A*x-b % ( )
