Math Problem Statement

Consider a 2x2 matrix A, where each element a_ij is an integer number that can take any value in the range of -10 to 10. What are the maximum and minimum possible values for the determinant det(A)? For a 3x3 matrix B, show that the determinant det(B) can be equal to -1000 or +1000, and provide other examples. Additionally, is -1000 the minimum value and +1000 the maximum value for det(B) in general?

Solution

Let's go through each part of this question.

Part A: 2x2 Matrix AA

  1. Finding the Maximum and Minimum Determinant for AA:
    • The determinant of a 2×22 \times 2 matrix A=[a11a12a21a22]A = \begin{bmatrix} a_{11} & a_{12} \\ a_{21} & a_{22} \end{bmatrix} is given by: det(A)=a11a22a12a21.\det(A) = a_{11}a_{22} - a_{12}a_{21}.
    • Each aija_{ij} can range from -10 to 10, so we need to maximize and minimize the product a11a22a12a21a_{11}a_{22} - a_{12}a_{21}.
    • Maximum value: occurs when a11=10a_{11} = 10, a22=10a_{22} = 10, a12=10a_{12} = -10, and a21=10a_{21} = -10. Thus, det(A)=(10)(10)(10)(10)=100100=0.\det(A) = (10)(10) - (-10)(-10) = 100 - 100 = 0.
    • Minimum value:

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Matrix Determinants

Formulas

det(A) = a_11 * a_22 - a_12 * a_21 for a 2x2 matrix
det(B) for a 3x3 matrix: b_11(b_22*b_33 - b_23*b_32) - b_12(b_21*b_33 - b_23*b_31) + b_13(b_21*b_32 - b_22*b_31)

Theorems

Determinant properties for square matrices

Suitable Grade Level

College or Advanced High School