I m unable to multiply two 4 cross 4 matrix ,how to solve this problem?

0.133681 cubic feet = 1 US Gallon
1357 cubic feet = x US Gallons

I set these up as a ratio and solve for the unknown by cross-multiplying.

In this case,

0.133681 1357
------------ = -------
1 x

Cross-multiplying (or multiplying both sides by x, same thing) we get 0.133681x = 1357. To get x by itself, we divide both sides by 0.133681 and we get x = 1357/0.133681.

Good luck.

Paul

Sorry, but your matrices do not make sense.If you multiply a matrix by a scalar the resulting (product) matrix has exactly the same structure as the one you multiplied : (mXn) times a yields another (mXn) matrix.
Be it as it may, when you multiply a matrix by a scalar, you obtain the product by multiplying every element of the original matrix by the scalar.

Here is a screen capture showing the multiplication of a 2X2 matrix by a scalar.



Note: I have noticed that screen captures I insert in my answers are sometimes deleted (by FixYa?). So if you do not see a picture it has nothing to do with me.

1. First you must set Matrix calculation: Press [MODE][6:Matrix].
2. Then by entering one of the numbers [1:MatA] or [2:Matb] or [3:MatC] you get to choose the dimensions of the matrix (mxn].
3. Once finished entering the matrix you clear the screen.
4. The operations on A SINGLE matrix are available by pressing [Shift][Matrix].
   
5. The choices are
   

• [1:Dim] to change the dimension of a matrix (in fact redefining the matrix)
• [2:Data] enter values in a matrix
• [3:MatA] access Matrix A
• [4:MatB] access Matrix B
• [5:MatC] access matrix C
• [6:MatAns] access the Answer Matrix (the last matrix calculated)
• [7:det] Calculate the determinant of a matrix already defined
• [8:Trn] The transpose of a matrix already defined

Once you have created a square matrix, for example matA.
You press [Shift][Matrix] [7:det] [SHIFT][MATRIX][3:MatA], close the parenthesis and press [ENTER].

If you have defined two similar matrices (same number of row and same number of columns) you can ADD them or subtract them. The operation keys are Plus and Minus as for any number.
To multiply you use the multiplication sign. The matrices must be compatible (mxn) multiplied by (nxk).

Matrix multiplication is defined only when the width of the first matrix is equal to the height of the second. You can multiply a 2x2 matrix by a 1x2 matrix or multiply a 2x1 matrix by a 2x2 matrix, but you cannot multiply a 2x2 matrix by a 2x1 matrix.

hi..

Its very easy to do matrix operations in FX 991ES
This calculator can operate up to three Matrices at a time, namely Matrix A (Mat A), Matrix B (MAT B), Matrix C(MAT C).

1. First to do, is set the calculator in MATRIX Mode
   Its Easy
   Press MODE button and press 6.
   Your Display will show indication of MAT on upper side of screen to show now calculator is in MATRIX Mode
   
   
2. Now we need to Define matrices and set its dimensions.
   This product supports matrix of order up to 3x3. That is you can operate matrix of No. of rows=3 and No. of columns=3
   To input matrix, Press SHIFT and then 4. This will Pop up Menu for Matrix. Now press 1
   Your screen will show as this,
   
   MAT A will be your First Matrix and MAT B will be your Second Matrix and so on.
   Press 1 , 2 , or 3 to select Matrix A , B, or C.
   here I will Proceed with Matrix A, so I press Numerical 1 Key
   
   
3. Next screen will ask you about the size of matrix.
   
   
   Press UP or DOWN Keys to view options.
   
   Press Corresponding Numerical keys to select corresponding order.
   
   
4. On Next Screen , enter values on each positions
   
   Press UP, DOWN, LEFT, RIGHT Keys to move around in matrix and specify each element.
   
   
5. Now we inputed Details about Matrix A. If you want to specify other matrices (MATRIX B, MATRIX C) repeat STEPS 2 To STEP 4
   
   
   
6. After Specifying required Matrices, we can tell calculator to do operations with them.
   
   Press SHIFT and then 4 and then It will show a menu contains
   
   
   
7. For example, i need to multiply Matrix A with Matrix B, i'll enter as
   
   SHIFT + 4 + 3 to Input Matrix A
   
   X to enter operator (Here multiplication, You enter + - x / for corresponding arithmetic operations )
   
   SHIFT + 4 + 4 to Input Matrix B
   
   = To show Result
   Press UP DOWN LEFT RIGHT Keys to view extra fields, if any.
   
   
   

Hope this will help you.

have a good time with Casio FX 991ES

I will not try to guess what you mean by "solve a matrix", but I believe that what follows will help you.

1. First you must set Matrix calculation: Press [MODE][6:Matrix].
2. Then by entering one of the numbers [1:MatA] or [2:Matb] or [3:MatC] you get to choose the dimensions of the matrix (mxn].
3. Once finished entering the matrix you clear the screen.
4. The operations on A SINGLE matrix are available by pressing [Shift][Matrix].
   
5. The choices are
   

• [1:Dim] to change the dimension of a matrix (in fact redefining the matrix)
• [2:Data] enter values in a matrix
• [3:MatA] access Matrix A
• [4:MatB] access Matrix B
• [5:MatC] access matrix C
• [6:MatAns] access the Answer Matrix (the last matrix calculated)
• [7:det] Calculate the determinant of a matrix already defined
• [8:Trn] The transpose of a matrix already defined

Once you have created a square matrix, for example matA.
You press [Shift][Matrix] [7:det] [SHIFT][MATRIX][3:MatA], close the parenthesis and press [ENTER].

If you have defined two similar matrices (same number of row and same number of columns) you can ADD them or subtract them. The operation keys are Plus and Minus as for any number.
To multiply you use the multiplication sign. The matrices must be compatible (mxn) multiplied by (nxk).

If you know the theory behind systems of linear equations you can use matrices to solve the systems.

1. First you must set Matrix calculation: Press [MODE][6:Matrix].
2. Then by entering one of the numbers [1:MatA] or [2:Matb] or [3:MatC] you get to choose the dimensions of the matrix (mxn].
3. Once finished entering the matrix you clear the screen.
4. The operations on A SINGLE matrix are available by pressing [Shift][Matrix].
   
5. The choices are
   

• [1:Dim] to change the dimension of a matrix (in fact redefining the matrix)
• [2:Data] enter values in a matrix
• [3:MatA] access Matrix A
• [4:MatB] access Matrix B
• [5:MatC] access matrix C
• [6:MatAns] access the Answer Matrix (the last matrix calculated)
• [7:det] Calculate the determinant of a matrix already defined
• [8:Trn] The transpose of a matrix already defined

Once you have created a square matrix, for example matA.
You press [Shift][Matrix] [7:det] [SHIFT][MATRIX][3:MatA], close the parenthesis and press [ENTER].

If you have defined two similar matrices (same number of row and same number of columns) you can ADD them or subtract them. The operation keys are Plus and Minus as for any number.
To multiply you use the multiplication sign. The matrices must be compatible (mxn) multiplied by (nxk).

Here check the manual:

http://support.casio.com/manualfile.php?rgn=5&cid=004001004

Let me explain how to create matrices. (If you know how to do it, skip to the operations on matricies, at the end.)

First you must set Matrix calculation
[MODE][6:Matrix]. Then By entering one of the numbers [1:MatA] or [2:Matb] or [3:MatC] you get to choose the dimensions of the matrix
(mxn]. Once finished entering the matrix you clear the screen.
The operations on matrices are available by pressing [Shift][Matrix]
[1:Dim] to change the dimension of a matrix (in fact redefining the matrix)
[2:Data] enter values in a matrix
[3:MatA] access Matrix A
[4:Matb] access Matrix B
[5:MatC] access matrix C
[6:MatAns] access the Answer Matrix (the last matrix calculated)
[7:det] Calculate the determinant of a matrix already defined
[8:Trn] The transpose of a matrix already defined

To add matrices MatA+MatB
To subtract MatA-MatB
To multiply MatAxMatB
To raise a matrixe to a power 2 [x2], cube [x3]
To obtain inverse of MatA already defined MatA[x-1] [x-1] is the x to the power -1 key
Dimensions of matrices involved in operations must match.
Here is a short summary

The multiplication of structured mathematical entities (vectors, complex numbers, matrices, etc.) is different from the multiplication of unstructured (scalar) mathematical entities (regular umbers). As you well know matrix multiplication is not commutative> This has to do with the dimensions.

An mXn matrix has m rows and n columns. To perform multiplication of an kXl matrice by an mXn matrix you multiply each element in one row of the first matrix by a specific element in a column of the second matrix. This imposes a condition, namely that the number of columns of the first matrix be equal to the number of rows of the second.
Thus, to be able to multiply a kXl matrix by am mXn matrix, the number of columns of the first (l) must be equal to the number of rows of the second (m).

So MatA(kXl) * MatB(mXn) is possible only if l=m
MatA(kX3) * Mat(3Xn) is possible and meaningful, but
Mat(kX3) * Mat(nX3) may not be possible.

To get back to your calculation, make sure that the number of columns of the first matrix is equal to the number of rows of the second. If this condition is not satisfied, the calculator returns a dimension error. The order of the matrices in the multiplication is, shall we say, vital.

Hello,
The so-called (2x1) matrix is not a matrix. It is a vector.
Hope it helps.