Let T : R4 --> R4 be the linear map satisfyingT{e1) =e2, T(e2) = e3...
We are given that a linear map
T : R4 --> R4 satisfying
T(e1) = e2, T(e2) = e3, T(e3) - 0, T(e4) = e3
Where {e1 e2, e3, e4} is the standard basis of R4.
Now, let (x,y,z,t) t ∈ R4.
Then (x,y,z,t) = [xe1 + ye2 + ze3 + te4]
Taking the image under linear transformation T, we get
T(x, y, z, t) = T[xe1 + ye2 + ze3 + te4] Using the linearity of T, we get
T(x, y, z, t) = xT(e1) + yT(e2) + zT(e3) + tT(e4)
Substituting the value of T(e1), T(e2), T(e3) and T(e4),
we get
T(x, y, z, t) = xe2 + ye3 + z • 0 + t • e3
or equivalently
T(x, y, z,t) = (0 ,x ,y + t,0)
Let (x, y, z, t) ∈ ker T.
Then T(x, y, z, t) = (0, 0, 0, 0)
Using the definition of linear transformation T, we get
(0, x , y + t, 0) = (0, 0, 0, 0)
Comparing the components, we get
x =0, y + t = 0, z is arbitrary.
Therefore, ker T = {(0, y, z, -y ) : yz ∈ R}.
Hence,dim ker T = 2.
Using rank nullity theorem
Rank T = 4 - dim ker T
= 4 - 2 = 2.
Now T2(x,y,z,t) = T[T(x, y, z, t)]
= T(0, x , y + t, 0) = (0, 0, x, 0)
and T3(x, y, z, t) = T[T2(x, y, z, t)]
= T(0,0,x,0)
= (0,0, 0 ,0 )
Hence, T is nilpotent linear transformation of index 3.