All Precalculus Resources
Example Questions
Example Question #1 : Find The Multiplicative Inverse Of A Matrix
What is the inverse of the following nxn matrix
The matrix is not invertible.
The matrix is not invertible.
Note the first and the last columns are equal.
Therefore, when we try to find the determinant using the following formula we get the determinant equaling 0:
This means simply, that the matrix does not have an inverse.
Example Question #1 : Find The Multiplicative Inverse Of A Matrix
Find the inverse of the matrix
.
Does not exist
Does not exist
For a 2x2 matrix
the inverse can be found by
Because the determinant is equal to zero in this problem, or
,
the inverse does not exist.
Example Question #2 : Find The Multiplicative Inverse Of A Matrix
Find the inverse of the matrix.
We use the inverse of a 2x2 matrix formula to determine the answer. Given a matrix
it's inverse is given by the formula:
First we define the determinant of our matrix:
Then,
Example Question #1 : Find The Multiplicative Inverse Of A Matrix
Find the inverse of the following matrix.
This matrix has no inverse.
This matrix has no inverse.
This matrix has no inverse because the columns are not linearly independent. This means if you row reduce to try to compute the inverse, one of the rows will have only zeros, which means there is no inverse.
Example Question #1 : Find The Multiplicative Inverse Of A Matrix
Find the multiplicative inverse of the following matrix:
This matrix has no inverse.
By writing the augmented matrix , and reducing the left side to the identity matrix, we can implement the same operations onto the right side, and we arrive at , with the right side representing the inverse of the original matrix.
Example Question #71 : Matrices And Vectors
Find the inverse of the matrix
None of the other answers.
There are a couple of ways to do this. I will use the determinant method.
First we need to find the determinant of this matrix, which is
for a matrix in the form:
.
Substituting in our values we find the determinant to be:
Now one formula for finding the inverse of the matrix is
.
Example Question #1 : Solve A System Of Equations Using The Multiplicative Inverse
What is the inverse of the identiy matrix ?
The identity matrix
The identity matrix
By definition, an inverse matrix is the matrix B that you would need to multiply matrix A by to get the identity. Since the identity matrix yields whatever matrix it is being multiplied by, the answer is the identity itself.
Example Question #1 : Solve A System Of Equations In Three Variables Using Augmented Matrices
Express this system of equations as an augmented matrix:
Arrange the equations into the form:
, where a,b,c,d are constants.
Then we have the system of equations: .
The augmented matrix is found by copying the constants into the respective rows and columns of a matrix.
The vertical line in the matrix is analogous to the = sign thus resulting in the following:
Example Question #2 : Solve A System Of Equations In Three Variables Using Augmented Matrices
Using an augmented matrix, solve the following system of equations:
Which of the following are the values of ,,and that satisfy this system?
Create an augmented matrix by entering the coefficients into one matrix and appending a vector to that matrix with the constants that the equations are equal to. Then you can row reduce to solve the system.
First, lets make this augmented matrix:
Now we can row reduce the matrix using the three row reduction operations: mutliply a row, add one row to another, swap row positions.
First, we can subtract .
Swap
Subtract
Add
Subtract
Mulitply
You can stop here given that this augmented matrix can be rewritten as a system again with
, or you can continue using the matrix, subtracting multiples of from the other two rows to get an identity matrix yielding the solution to the system.
Example Question #14 : Finite Mathematics
True or false: there is no solution that makes this matrix equation true.
True
False
False
For two matrices to be equal, two conditions must hold:
1) The matrices must have the same dimension. This can be seen to be the case, since both matrices have two rows and one column.
2) All corresponding entries must be equal. For this to happen, it must hold that
This is a system of two equations in two variables, which can be solved as follows:
Add both sides of the equations:
It follows that
Substitute back:
Thus, there exists a solution to the system, and, consequently, to the original matrix equation. The statement is therefore false.