Math Problem Statement

Let x, y, and z be 3 linearly independent vectors in R^n. Are the vectors (x-y), (y-z), (z-x) linearly independent? Are the vectors (x+y), (y+z), (z+x) linearly independent?

Solution

The problem you provided asks about the linear independence of two sets of vectors formed from three given linearly independent vectors x,y,x, y, and zz in Rn\mathbb{R}^n.

Part (a)

Question: Are the vectors (xy),(yz),(zx)(x - y), (y - z), (z - x) linearly independent?

To determine the linear independence of (xy),(yz),(zx)(x - y), (y - z), (z - x), we check if the only solution to the equation a(xy)+b(yz)+c(zx)=0a(x-y) + b(y-z) + c(z-x) = 0 is a=b=c=0a = b = c = 0.

Expanding and rearranging the terms, we get: axay+bybz+czcx=0a x - a y + b y - b z + c z - c x = 0 (ac)x+(ba)y+(cb)z=0(a - c)x + (b - a)y + (c - b)z = 0

Since x,y,x, y, and zz are linearly independent, the coefficients of x,y,x, y, and zz must each be zero: ac=0a - c = 0 ba=0b - a = 0 cb=0c - b = 0

These equations imply a=b=ca = b = c. This means the equation can be true for any non-zero scalar a=b=c0a = b = c \neq 0. Hence, the vectors (xy),(yz),(zx)(x-y), (y-z), (z-x) are not linearly independent as they are linearly dependent on each other.

Part (b)

Question: Are the vectors (x+y),(y+z),(z+x)(x + y), (y + z), (z + x) linearly independent?

To determine the linear independence of (x+y),(y+z),(z+x)(x + y), (y + z), (z + x), we consider the equation: a(x+y)+b(y+z)+c(z+x)=0a(x+y) + b(y+z) + c(z+x) = 0

Expanding this, we get: ax+ay+by+bz+cz+cx=0a x + a y + b y + b z + c z + c x = 0 (a+c)x+(a+b)y+(b+c)z=0(a + c)x + (a + b)y + (b + c)z = 0

Again, using the linear independence of x,y,x, y, and zz, we must have: a+c=0a + c = 0 a+b=0a + b = 0 b+c=0b + c = 0

These equations imply a=b,b=c,a = -b, b = -c, and c=ac = -a. Solving these gives a=b=c=0a = b = c = 0. Hence, the vectors (x+y),(y+z),(z+x)(x + y), (y + z), (z + x) are linearly independent.

Would you like further details on any part or have any other questions about linear independence or vector spaces? Here are some related questions and a tip:

  1. How can you determine linear independence in higher dimensions?
  2. What other types of vector operations might affect linear independence?
  3. Can adding more vectors to a set ever lead to a loss of linear independence?
  4. What are the implications of linear independence in solving systems of linear equations?
  5. How do properties of linear independence apply to function spaces?

Tip: When solving problems involving vector independence, organizing terms by vector components can simplify the visualization of the problem and solutions.

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Math Problem Analysis

Mathematical Concepts

Linear Independence
Vector Spaces
Algebra

Formulas

Linear combination equation: a(x-y) + b(y-z) + c(z-x) = 0
Linear combination equation: a(x+y) + b(y+z) + c(z+x) = 0

Theorems

Linear Independence Theorem: If a linear combination of vectors is equal to zero, and the only solution for the coefficients is the trivial solution (all coefficients equal to zero), then the vectors are linearly independent.

Suitable Grade Level

Undergraduate (Math/Economics courses)