<Dd> (1 4 1 0 6 4 0 0 1) (\ displaystyle (\ begin (bmatrix) 1&4&1 \ \ 0&6&4 \ \ 0&0&1 \ \ \ end (bmatrix))) </Dd> <P> is upper triangular and this matrix </P> <Dl> <Dd> (1 0 0 2 8 0 4 9 7) (\ displaystyle (\ begin (bmatrix) 1&0&0 \ \ 2&8&0 \ \ 4&9&7 \ \ \ end (bmatrix))) </Dd> </Dl> <Dd> (1 0 0 2 8 0 4 9 7) (\ displaystyle (\ begin (bmatrix) 1&0&0 \ \ 2&8&0 \ \ 4&9&7 \ \ \ end (bmatrix))) </Dd>

Give an example of a 3×3 lower triangular matrix a that is not diagonal