Math Problem Statement

Let matrix A = [[-2, 0], [3, 1]] and matrix B = [[2k - 1, 1], [2, k + 1]], where k is a constant. Determine the value(s) of k if matrix B is singular.

Solution

Let's first address the second part of the question:

Matrix BB: B=[2k112k+1]B = \begin{bmatrix} 2k - 1 & 1 \\ 2 & k + 1 \end{bmatrix} We are asked to find the value(s) of kk that make matrix BB singular.

Step 1: Definition of Singular Matrix

A matrix is singular if and only if its determinant is zero.

Step 2: Determinant of Matrix BB

The determinant of a 2x2 matrix [abcd]\begin{bmatrix} a & b \\ c & d \end{bmatrix} is calculated as: det(B)=(ad)(bc)\text{det}(B) = (a \cdot d) - (b \cdot c) For matrix BB: det(B)=(2k1)(k+1)(12)\text{det}(B) = (2k - 1)(k + 1) - (1 \cdot 2)

Step 3: Solve for the Determinant

Let's expand the determinant: det(B)=(2k1)(k+1)2\text{det}(B) = (2k - 1)(k + 1) - 2 Expanding the product: det(B)=(2k2+2kk1)2\text{det}(B) = (2k^2 + 2k - k - 1) - 2 Simplifying: det(B)=2k2+k12=2k2+k3\text{det}(B) = 2k^2 + k - 1 - 2 = 2k^2 + k - 3

Step 4: Set the Determinant to Zero

To make BB singular, set the determinant equal to zero: 2k2+k3=02k^2 + k - 3 = 0

Step 5: Solve the Quadratic Equation

We can solve this quadratic equation using the quadratic formula: k=b±b24ac2ak = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} Where a=2a = 2, b=1b = 1, and c=3c = -3.

Let's solve for kk.The values of kk that make matrix BB singular are: k=1ork=1.5k = 1 \quad \text{or} \quad k = -1.5

Would you like any further details or clarifications?

Here are 5 related questions:

  1. How do you determine if a matrix is invertible?
  2. Can you explain how the determinant of a matrix affects its singularity?
  3. What is the geometric interpretation of a singular matrix?
  4. How does changing kk affect the determinant of matrix BB?
  5. How can matrix AA in the problem be used in further calculations with matrix BB?

Tip: For quadratic equations, always check the discriminant b24acb^2 - 4ac first. If it’s negative, the equation has no real solutions.

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Math Problem Analysis

Mathematical Concepts

Algebra
Matrices
Determinants
Quadratic Equations

Formulas

Determinant of 2x2 matrix: det(B) = (a * d) - (b * c)
Quadratic equation formula: k = (-b ± √(b^2 - 4ac)) / 2a

Theorems

Determinant and Singularity
Quadratic Formula

Suitable Grade Level

Grades 11-12 (Pre-Calculus or Algebra II)