Find det(A - nIn), where A is an n x n matrix whose entries are all 1, and In is the n x n identity matrix.

The nxn identity matrix, is an nxn matrix whose diagonal elements are all equal to 1, and all other (non-diagonal) elements are equal to 0.

One example: the determinant of a 4x4 identity matrix is 1.

Use the matrix editor to create a 4x4 matrix with 1s along the main diagonal (upper-left to lower-right) and 0s elsewhere. Then use the det() function to calculate the determinant of this matrix.

Here is a detailed account of how to calculate the determinant of a square matrix.

I assume you know how to define your matrix, but I will repeat it here for others who might not know. You can skip to Calculation
1.Turn Calculator ON. If there are no icons, press [MENU].

Data Entry
2.Use arrows to highlight [MAT] icon. Press [ENTER]
3.Highlight the first line where it says Mat A. Use the right arrow to enter the dimensions of Matrix A. Enter 3 and press [EXE]. The cursor moves to the second dimension. Press 3 and press [ENTER].
4. The matrix entry screen appears.
5. Enter first matrix coefficient a_11 and press [ENTER]
6. Enter a_12 and [ENTER]
.....
Key in last coefficient a_33 and press [ENTER]

Calculation
Press [MENU] and [RUN]
Press [OPTN][F2:MAT][F3:Det] Command echoes on screen as det
Press [F1:Mat] echoes on screen as Mat; screen shows det Mat
Press [ALPHA] A The screen displays det Mat A
Press [ENTER] to calculate the determinant.

If the matrix is not square, you cannot calculate its determinant.

When you press the OPTN key you see Tabs at the bottom of the screen. The second one from the left should be the submenu for matrix operations.. When you press F2:MAT, the new tabs are Mat, M>L (Matrix to List), Det (command to calculate the determinant etc.

Here is a detailed account of how to calculate the determinant of a square matrix.

I assume you know how to define your matrix, but I will repeat it here for others who might not know. You can skip to Calculation
1.Turn Calculator ON. If there are no icons, press [MENU].

Data Entry
2.Use arrows to highlight [MAT] icon. Press [ENTER]
3.Highlight the first line where it says Mat A. Use the right arrow to enter the dimensions of Matrix A. Enter 3 and press [EXE]. The cursor moves to the second dimension. Press 3 and press [ENTER].
4. The matrix entry screen appears.
5. Enter first matrix coefficient a_11 and press [ENTER]
6. Enter a_12 and [ENTER]
.....
Key in last coefficient a_33 and press [ENTER]

Calculation
Press [MENU] and [RUN]
Press [OPTN][F2:MAT][F3:Det] Command echoes on screen as det
Press [F1:Mat] echoes on screen as Mat; screen shows det Mat
Press [ALPHA] A The screen displays det Mat A
Press [ENTER] to calculate the determinant.

If the matrix is not square, you cannot calculate its determinant.

When you press the OPTN key you see Tabs at the bottom of the screen. The second one from the left should be the submenu for matrix operations.. When you press F2:MAT, the new tabs are Mat, M>L (Matrix to List), det (command to calculate the determinant etc.

Here is a detailed account of how to calculate the determinant of a square matrix.

I assume you know how to define your matrix, but I will repeat it here for others who might not know. You can skip to Calculation
1.Turn Calculator ON. If there are no icons, press [MENU].

Data Entry
2.Use arrows to highlight [MAT] icon. Press [ENTER]
3.Highlight the first line where it says Mat A. Use the right arrow to enter the dimensions of Matrix A. Enter 3 and press [EXE]. The cursor moves to the second dimension. Press 3 and press [ENTER].
4. The matrix entry screen appears.
5. Enter first matrix coefficient a_11 and press [ENTER]
6. Enter a_12 and [ENTER]
.....
Key in last coefficient a_33 and press [ENTER]

Calculation
Press [MENU] and [RUN]
Press [OPTN][F2:MAT][F3:Det] Command echoes on screen as det
Press [F1:Mat] echoes on screen as Mat; screen shows det Mat
Press [ALPHA] A The screen displays det Mat A
Press [ENTER] to calculate the determinant.

If the matrix is not square, you cannot calculate its determinant.

Since the largest matrix you can create on the FX-115ES is a 3X3 matrix, I am not sure it is worth it to do it on a calculator.

There is no command on the calculator that allows you to do it.
You can use the calculator to evaluate the minors for each element (the determinant of the matrix that is left when you remove the column and the row that have that element as intersection).
Here is an example how to calculate the cofactor of the _11 element of a 3X3 matrix.

1. I defined a 3x3 matrix called b
2. I defined a submatrix by removing the first row and the first column of the b matrix.
   
3. The submatrix is called min11.
   
4. Its determinant is the minor of the _11 element of matrix b.
5. The cofactor cof11 of _11 element of matrix b is the product of (-1) to the the power (1+1) and the minor of the _11 element.
6. The cofactor is represented by the last result to the right of ->cof11, that means b22*b33-b23*b32. The cofactor is a number.
   
7. For additional information refer to your algebra book.

Note: The power of -1 that multiplies the minor of an element is
(-1)^(row number + column number).
coff11=((-1)^2)*det(min11) =det(min11)
cof12=((-1)^(1+2))* det(min12)=-det(min12)
cof13=((-1)^(1+3))*det(min13)= det(min13)
cof21=((-1)^(1+2))*det(min21)= -det(min21)
etc.

Hello,
I assume yoy know how to define your matrix, but I will repeat it here for others who might not know. You can skip to Calculation
1.Turn Calculator ON. If there are no icons, press [MENU].

Data Entry
2.Use arrows to highlight [MAT] icon. Press [ENTER]
3.Highlight the first line where it says Mat A. Use the right arrow to enter the dimensions of Matrix A. Enter 3 and press [EXE]. The cursor moves to the second dimension. Press 3 and press [ENTER].
4. The matrix entry screen appears.
5. Enter first matrix coefficient a_11 and press [ENTER]
6. Enter a_12 and [ENTER]
.....
Key in last coefficient a_33 and press [ENTER]

Calculation
Press [MENU] and [RUN]
Press [OPTN][F2:MAT][F3:Det] Command echoes on screen as det
Press [F1:Mat] echoes on screen as Mat; screen shows det Mat
Press [ALPHA] A The screen displays det Mat A
Press [ENTER] to calculate the determinant.

If the matrix is not square, you cannot calculate its determinant.

Hope it helps..

Hello,
I will assume you are familiar with the basic concepts of matrix algebra.

Turn calculator [ON]
Press [MODE][6:MATRIX]. Select the matrix you want: MatA, MatB, Matc
Let us assume you select 1: MatA.
MatA (mxn) sceen: there you specify the dimensions of the matrix, the number of rows, and the number of columns. Press 5 for a 2x2 matrix.
The matrix entry screen shows, a rectangle is highlighted. Enter there the a_11 coefficient, exemple 1.
1 [ENTER]. Highlight moves to a_12 ;
1 [ENTER] highlight moves to a_21
1 [ENTER] highlight moves to a_22
2 [ENTER] Highlight stays on a_22.
Matrix is defined. The values I used are arbitrary. Enter your own.

Suppose you want to calculate the determinant of MatA
Press [SHIFT][MATRIX][7:det][SHIFT][MATRIX][3:MatA] [)] [=]

Now you want to calculate the square of matA.
Press [SHIFT][MATRIX][3:MatA] [x^2][=]
A 2x2 matrix is displayed. It is MatA[^2].

If you define MatA, MatB, MatC y

I solve your problem but there is a little mistake that I can't find but maybe you can so here what I wrote:

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
#include <dos.h>
#include <math.h>

#define n 3

typedef struct
{
double A[n][n];
int size;
}Matrix;

double det(Matrix mat);
Matrix cut(Matrix mat, int x);
int main(void)
{
clrscr();
double d;
Matrix mat;
mat.size=n;
mat.A[0][0]=1;
mat.A[0][1]=2;
mat.A[0][2]=3;
mat.A[1][0]=4;
mat.A[1][1]=4;
mat.A[1][2]=6;
mat.A[2][0]=7;
mat.A[2][1]=8;
mat.A[2][2]=9;

d=det(mat);
printf("%d",d);
getch();
return 0;
}
double det(Matrix mat)
{
double d=0;
if(mat.size>2)

for(int i=0;i<mat.size;i++)

d+=pow(-1,i)*mat.A[0][i]*det(cut(mat,i));

else

d=mat.A[0][0]*mat.A[1][1]-mat.A[0][1]*mat.A[1][0];

return d;
}
Matrix cut(Matrix mat, int x)
{
Matrix cutmat;
cutmat.size=mat.size-1;
for(int i=0;i<cutmat.size;i++)
for(int j=0;j<cutmat.size;j++)
if(j<x)
cutmat.A[i][j]=mat.A[i+1][j];
else
cutmat.A[i][j]=mat.A[i+1][j+1];
return cutmat;
}
Rate me if it helped!
And if you find the mistake please tell me where thanks.

the cofactor (C) of Matrix (A) = (det(a) times (A)^-1)t

Cof A=(detAxA^1)t

Enter a matrix for (MatA) AC
shift 4 7 gives det(_
shift 4 3 shows det(a )<-end Paren
= x shows ansx
shift 4 3 shows ansxMatA -1x
= you'll see a Matrix AC to get out
shift 4 8 gives Trn(
shift 4 6 shows Trn(MatAns) =


The Matrix graph shows all the Cofactors