Linear transformaton and inverse

In summary, the conversation discusses the conditions for a linear transformation T: V → W to have an inverse T^-1: V → W. It is stated that if T is an injective linear transformation, then T^-1 is a function from V to W. However, it is then clarified that T must also be surjective in order for T^-1 to be a linear transformation. Finally, the conversation ends with a prompt to prove this statement by explicitly defining T^-1.
  • #1
autre
117
0

Homework Statement



If T : V → W is an injective linear transformation, then T^-1: V →W is a linear transformation.

The Attempt at a Solution



Let w1, w2 in W. If w1=T(v1) and w2=T(v2), v1=/=v2 in V. Thus, T^-1: V →W is a function. Then, v1+v2=T^-1(w1) + T^-1(w2) and for a in F, T^-1(w1) = aT^-1(w1) = av1 for w in W.
 
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  • #2
autre said:
If T : V → W is an injective linear transformation, then T^-1: V →W is a linear transformation.

This is not true. Injectivity is not enough. You need bijectivity.
 
  • #3
Oh sorry, I left out a part. T:V -> W is a linear transformation, T(V) is a subspace of W.
 
  • #4
micromass said:
This is not true. Injectivity is not enough. You need bijectivity.

but doesn't he have to use injectivity and surjectivity to show bijectivity?
 
  • #5
autre said:
Oh sorry, I left out a part. T:V -> W is a linear transformation, T(V) is a subspace of W.

Not enough. You need T to be surjective.

mtayab1994 said:
but doesn't he have to use injectivity and surjectivity to show bijectivity?

Yes, but he didn't state that T is surjective.
 
  • #6
what IS true, is that if T:V→W is an injective linear transformation, then

T-1:T(V)→V is a linear transformation.

now, prove this by explicitly defining what T-1 has to be.
 

1. What is a linear transformation?

A linear transformation is a mathematical operation that maps a vector from one vector space to another, while preserving the structure of the vector space. In simpler terms, it is a function that takes in a vector as input and outputs a different vector.

2. What is the inverse of a linear transformation?

The inverse of a linear transformation is a function that "undoes" the original transformation, such that when the two functions are composed together, they result in the identity function. In other words, the inverse of a linear transformation "reverses" the effects of the original transformation.

3. How is a linear transformation represented mathematically?

A linear transformation can be represented by a square matrix. Each column of the matrix represents the transformation of a standard basis vector in the original vector space. The resulting vector after the transformation can be found by multiplying the matrix by the input vector.

4. What is the importance of inverse linear transformations?

Inverse linear transformations are important because they allow us to "undo" a transformation and retrieve the original vector. They are also useful in solving systems of linear equations and performing other mathematical operations.

5. Are all linear transformations invertible?

No, not all linear transformations are invertible. A linear transformation is invertible if and only if its associated matrix is nonsingular, meaning it has a nonzero determinant. If the matrix is singular, the transformation is not invertible and the inverse does not exist.

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