More formally, if T is a linear transformation from a vector space V over a field F into itself and v is a vector in V that is not the zero vector, then v is an Eigenvector of T if T(v) is a scalar multiple of v. This condition can be written as the equation
T(V) =λv
Below Matrix A acts by stretching the vector x, not changing its direction, so x is an Eigenvector of A.