Math Problem Statement

Is the vector b = [-42, -16, -4] in the span of the vectors a1 = [-9, -8, 4] and a2 = [-1, -8, 8]? If so, find the coefficients.

Solution

The problem asks whether the vector b is in the span of the vectors a₁ and a₂. We need to determine if there exist scalars x1x_1 and x2x_2 such that:

b=x1a1+x2a2b = x_1 a_1 + x_2 a_2

This translates to solving the following vector equation:

(42164)=x1(984)+x2(188)\begin{pmatrix} -42 \\ -16 \\ -4 \end{pmatrix} = x_1 \begin{pmatrix} -9 \\ -8 \\ 4 \end{pmatrix} + x_2 \begin{pmatrix} -1 \\ -8 \\ 8 \end{pmatrix}

To solve this, we can set up the corresponding system of linear equations:

  1. 42=9x1x2-42 = -9x_1 - x_2
  2. 16=8x18x2-16 = -8x_1 - 8x_2
  3. 4=4x1+8x2-4 = 4x_1 + 8x_2

Let me solve this system to check if a solution exists.The solution to the system of equations is x1=5x_1 = 5 and x2=3x_2 = -3. This means that the vector b is in the span of the vectors a₁ and a₂, and we can express:

b=5a13a2b = 5a_1 - 3a_2

Thus, the correct answer is:

  • A. Yes, b is in the span.

The coefficients are:

  • x1=5x_1 = 5
  • x2=3x_2 = -3

Would you like a further explanation on how to solve the system of equations?

Here are some related questions to expand your understanding:

  1. How do you determine if vectors are linearly independent?
  2. What does it mean for a set of vectors to span a vector space?
  3. Can vectors spanning a space form a basis for that space?
  4. How can matrix methods (e.g., row reduction) be used to check if vectors are in a span?
  5. What is the geometric interpretation of a vector being in the span of two others?

Tip: When solving systems of equations, ensure you align the corresponding components of each vector to form the correct system of linear equations.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Vector Span
System of Linear Equations

Formulas

b = x1 * a1 + x2 * a2
System of equations for vector components: -42 = -9x1 - x2, -16 = -8x1 - 8x2, -4 = 4x1 + 8x2

Theorems

Span of Vectors

Suitable Grade Level

Grades 10-12