Matrices



Solutions
The following is the MAPLE sheet to solve these two examples.
> with(linalg);
Warning, the protected names norm and trace have been redefined and unprotected
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> A:=matrix(3,3,[2,-3,2,0,-1,7,6,-1,1]);
![A := matrix([[2, -3, 2], [0, -1, 7], [6, -1, 1]])](file:///E:\..\..\matrices11.gif)
> B:=matrix(3,3,[-1,1,5,2,-3,1,9,0,-2]);
![B := matrix([[-1, 1, 5], [2, -3, 1], [9, 0, -2]])](file:///E:\..\..\matrices12.gif)
> C:=matrix(3,1,[5,1,3]);
![C := matrix([[5], [1], [3]])](file:///E:\..\..\matrices13.gif)
> X:=matrix(3,1,[x^2,ln(x),(1-x)]);
![X := matrix([[x^2], [ln(x)], [1-x]])](file:///E:\..\..\matrices14.gif)
> evalm(2*B);
![matrix([[-2, 2, 10], [4, -6, 2], [18, 0, -4]])](file:///E:\..\..\matrices15.gif)
> #b]
> V:=multiply(A,B);
![V := matrix([[10, 11, 3], [61, 3, -15], [1, 9, 27]]...](file:///E:\..\..\matrices16.gif)
> #c]
> multiply(A,inverse(A));
![matrix([[1, 0, 0], [0, 1, 0], [0, 0, 1]])](file:///E:\..\..\matrices17.gif)
> #d]
> inverse(V);
![matrix([[-18/1207, 45/2414, 29/2414], [277/2414, -8...](file:///E:\..\..\matrices18.gif)
> transpose(B);
![matrix([[-1, 2, 9], [1, -3, 0], [5, 1, -2]])](file:///E:\..\..\matrices19.gif)
> transpose(multiply(B,C));
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> #g]
> evalm(-10*V);
![matrix([[-100, -110, -30], [-610, -30, 150], [-10, ...](file:///E:\..\..\matrices21.gif)
> #h]
> evalm(A^3);
![matrix([[-58, -28, -18], [84, -120, 42], [72, -42, ...](file:///E:\..\..\matrices22.gif)
> #j]
> matadd(multiply(A,C),X);
![matrix([[13+x^2], [20+ln(x)], [33-x]])](file:///E:\..\..\matrices23.gif)
> #i]
> evalm(-10*multiply(A,X));
![matrix([[-20*x^2+30*ln(x)-20+20*x], [-70+10*ln(x)+7...](file:///E:\..\..\matrices24.gif)
> #k]
> det(transpose(B));
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> #l]
> evalm(det(inverse(evalm(A^3)))*B);
![matrix([[1/1061208, -1/1061208, -5/1061208], [-1/53...](file:///E:\..\..\matrices26.gif)
>
> #EXample 2
> A:=matrix(2,2,[6,-5,-2,9]);
![A := matrix([[6, -5], [-2, 9]])](file:///E:\..\..\matrices27.gif)
> eigenvects(A);
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> v1:=matrix(2,1,[1,-1]);
![v1 := matrix([[1], [-1]])](file:///E:\..\..\matrices29.gif)
> v2:=matrix(2,1,[5/2,1]);
![v2 := matrix([[5/2], [1]])](file:///E:\..\..\matrices30.gif)
> evalm(A&*v1=11*v1);
![matrix([[11], [-11]]) = matrix([[11], [-11]])](file:///E:\..\..\matrices31.gif)
> evalm(A&*v2=4*v2);
![matrix([[10], [4]]) = matrix([[10], [4]])](file:///E:\..\..\matrices32.gif)
> #b]
> A:=matrix(3,3,[-4,0,6,2,4,-4,2,0,7]);
![A := matrix([[-4, 0, 6], [2, 4, -4], [2, 0, 7]])](file:///E:\..\..\matrices33.gif)
> eigenvects(A);
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> v1:=matrix(3,1,[-6,16/9,1]):v2:=matrix(3,1,[0,1,0]):v3:=matrix(3,1,[1,-3/2,2]):
> evalm(A&*v1=-5*v1);
![matrix([[30], [-80/9], [-5]]) = matrix([[30], [-80/...](file:///E:\..\..\matrices35.gif)
> evalm(A&*v2=4*v2);
![matrix([[0], [4], [0]]) = matrix([[0], [4], [0]])](file:///E:\..\..\matrices36.gif)
> evalm(A&*v3=8*v3);
![matrix([[8], [-12], [16]]) = matrix([[8], [-12], [1...](file:///E:\..\..\matrices37.gif)
> #c]
> A:=matrix(3,3,[2,-3,1,2,-3,0,6,-45,12]);
![A := matrix([[2, -3, 1], [2, -3, 0], [6, -45, 12]])...](file:///E:\..\..\matrices38.gif)
> charpoly(A,lambda);
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> eigenvects(A);
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Ø # the rest of the example is left as an exercise.
Ø