For which value of b {\textstyle b} does the matrix A {\textstyle A} below have two linearly independent eigenvectors corresponding to the eigenvalue λ = 1 {\textstyle \lambda =1} ?
![{\displaystyle A=\left[{\begin{array}{ccc}1&-4&b\\0&3&3\\0&0&1\end{array}}\right]}](https://wiki.ubc.ca/api/rest_v1/media/math/render/svg/80e77dc0e8ac272597f235ddfa80ce39933fb2fb)