Determinants as Area or Volume

In summary, we are given a parallelepiped S and a linear transformation T: R3-->R3 determined by a 3x3 matrix A. The volume of T(S) can be calculated by taking the determinant of A and multiplying it by the volume of S. Some confusion arises as the given answer is 24, while the calculated determinant of A is 9. Further clarification and rechecking of calculations may be needed.
  • #1
Lonely Lemon
22
0

Homework Statement



If S is a parallelepiped determined by v1=(1, 1, 0) and v2= (3, 2, 1) and v3=(6, 1, 2) and T: R3--> R3 by T(x)=Ax, find the volume of T(S)

Homework Equations



{volume of T(S)}=|det A|.{volume of S}

The Attempt at a Solution



A is [v1 v2 v3] and the |A| = 9 by my calculations. I thought this was the volume, but the answer to the questions is given as 24. Please help!
 
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  • #2
So the vectors define both the solid S and the mapping A? Just want to make sure you've described the problem as assigned.
 
  • #3
I assume so, that's the problem posed word for word. T: R3-->R3 is the linear transformation determined by a 3x3 matrix A, and S is the a parallelepiped in R3, so the vectors define both?
 
  • #4
If that's true, then shouldn't the volume of T(S) be a perfect square? By the way, I get det A=3, so you might want to recheck your calculations.
 

Related to Determinants as Area or Volume

1. What is a determinant and how is it related to area or volume?

A determinant is a mathematical concept used to describe the size, shape, and orientation of a geometric object. In the context of linear algebra, the determinant of a matrix represents the scaling factor of the area or volume of the parallelogram or parallelepiped formed by the column vectors of the matrix.

2. How do you calculate the determinant of a matrix?

The determinant of a 2x2 matrix can be calculated by multiplying the values in the main diagonal and subtracting the product of the values in the off-diagonal. For larger matrices, the calculation can be done using various methods such as row reduction or cofactor expansion.

3. Can the determinant be negative?

Yes, the determinant can be negative. The sign of the determinant depends on the orientation of the column vectors of the matrix. If the orientation is reversed, the determinant will have the opposite sign. This can also be interpreted as a change in direction for the area or volume of the geometric object.

4. How is the determinant used to solve systems of linear equations?

The determinant can be used to determine the number of solutions for a system of linear equations. If the determinant is non-zero, then the system has a unique solution. If the determinant is zero, then the system has either no solution or infinite solutions, depending on the consistency of the equations.

5. Are there any real-world applications of determinants as area or volume?

Yes, there are many real-world applications of determinants as area or volume. For example, in physics, the determinant can be used to calculate the moment of inertia of an object, which is important in understanding the object's rotational motion. In engineering, the determinant is used in calculating the stress and strain of an object under different forces. It also has applications in computer graphics for determining the size and orientation of 3D objects.

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