Let A be a n × n matrix, Suppose that A has n distinct eigenvalues λ1, . . . , λn, and corresponding non-zero eigenvectorsx1, . . . , xn. Prove that {x1, . . . , xn} are linearly independent.Hint: You may use without proof the following property: If {y1, . . . , ym} are linearly dependentthen there exists some p such that 1 ≤ p < m, yp+1 ∈ span{y1, . . . , yp} and {y1, . . . , yp} arelinearly independent.
Question
Let A be a n × n matrix, Suppose that A has n distinct eigenvalues λ1, . . . , λn, and corresponding non-zero eigenvectorsx1, . . . , xn. Prove that {x1, . . . , xn} are linearly independent.Hint: You may use without proof the following property: If {y1, . . . , ym} are linearly dependentthen there exists some p such that 1 ≤ p < m, yp+1 ∈ span{y1, . . . , yp} and {y1, . . . , yp} arelinearly independent.
Solution
To prove that the set of eigenvectors {x1, . . . , xn} are linearly independent, we will use a proof by contradiction.
Assume that the set of eigenvectors {x1, . . . , xn} are linearly dependent. According to the hint, this means that there exists some p such that 1 ≤ p < n, xp+1 ∈ span{ x1, . . . , xp } and { x1, . . . , xp } are linearly independent.
This means that we can write xp+1 as a linear combination of the previous vectors:
xp+1 = a1x1 + a2x2 + ... + ap*xp
Now, let's multiply both sides of this equation by A (the matrix):
Axp+1 = a1Ax1 + a2Ax2 + ... + apA*xp
We know that Axi = λixi for each i (from the definition of eigenvalues and eigenvectors), so we can substitute these into the equation:
λp+1xp+1 = a1λ1x1 + a2λ2x2 + ... + apλp*xp
Subtract the original linear combination equation from this one:
λp+1xp+1 - (a1x1 + a2x2 + ... + apxp) = a1*(λ1 - λp+1)x1 + a2(λ2 - λp+1)x2 + ... + ap(λp - λp+1)*xp
The left side of this equation is zero, because xp+1 is a linear combination of the other vectors. So, we have:
0 = a1*(λ1 - λp+1)x1 + a2(λ2 - λp+1)x2 + ... + ap(λp - λp+1)*xp
This is a linear combination of {x1, . . . , xp}, which we assumed to be linearly independent. A linear combination of linearly independent vectors can only be zero if all the coefficients are zero.
But, since λi ≠ λp+1 for all i (because all eigenvalues are distinct), the coefficients a1*(λ1 - λp+1), a2*(λ2 - λp+1), ..., ap*(λp - λp+1) cannot all be zero unless a1, a2, ..., ap are all zero.
This contradicts our assumption that xp+1 can be written as a linear combination of the previous vectors. Therefore, our original assumption that the set of eigenvectors {x1, . . . , xn} are linearly dependent must be false.
So, we conclude that the set of eigenvectors {x1, . . . , xn} are linearly independent.
Similar Questions
An n×n matrix A is diagonalizable if A has n linearly independent eigenvectors.A. TrueB. False
If 0 is an Eigen value of a matrix A, then the set of columns of A isQuestion 5Select one:Linearly independent always.Linearly independent or linearly dependent..Cannot be determined.Linearly dependent always.
Every linear operator in an n-dimensional vector space has n distinct eigen-values
Let and be any three non-zero vectors. Then, is independent ofx
Show that (8 pts) A2023 and B2023 are similar and (4 pts) have the same eigen-values.6 (10 pts) Let λ1 and λ2 be two distinct eigenvalues of an n × n matrix A. Let v1 and v2 betheir corresponding eigenvactors, respectively. Show that v1 and v2 are linearly independen
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.