# Quick Answer: Is a linear transformation injective?

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## How do you know if a linear transformation is injective?

To test injectivity, one simply needs to see if the dimension of the kernel is 0. If it is nonzero, then the zero vector and at least one nonzero vector have outputs equal 0W, implying that the linear transformation is not injective. Conversely, assume that ker(T) has dimension 0 and take any x,y∈V such that T(x)=T(y).

## Is a linear transformation surjective?

A linear transformation T from a vector space V to a vector space W is called an isomorphism of vector spaces if T is both injective and surjective. If a linear transformation is an isomorphism and is defined by multiplication by a matrix, explain why the matrix must be square.

## Can a linear transformation be injective but not surjective?

(Fundamental Theorem of Linear Algebra) If V is finite dimensional, then both kerT and R(T) are finite dimensional and dimV = dim kerT + dimR(T). If dimV = dimW, then T is injective if and only if T is surjective.

## Is a linear transformation Bijective?

A linear transformation can be bijective only if its domain and co-domain space have the same dimension, so that its matrix is a square matrix, and that square matrix has full rank.

## Is linear functional injective?

A linear transformation is injective if and only if its kernel is the trivial subspace {0}. Example. This is completely false for non-linear functions. For example, the map f : R → R with f(x) = x2 was seen above to not be injective, but its “kernel” is zero as f(x)=0 implies that x = 0.

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## What is an injective matrix?

Let A be a matrix and let Ared be the row reduced form of A. If Ared has a leading 1 in every column, then A is injective. If Ared has a column without a leading 1 in it, then A is not injective. Invertible maps. If a map is both injective and surjective, it is called invertible.

## Can a matrix be injective but not surjective?

For square matrices, you have both properties at once (or neither). If it has full rank, the matrix is injective and surjective (and thus bijective).

## Is a transformation linear?

A linear transformation is a function from one vector space to another that respects the underlying (linear) structure of each vector space. A linear transformation is also known as a linear operator or map. … The two vector spaces must have the same underlying field.