1. is Diagonally Dominant Matrix ?
`[[-3,0,0],[0,-2,0],[0,0,-1]]`

Solution:
A Square matrix `A` is called diagonally dominant matrix, if `A_(ii)>=sum_(i!=j)^()|A_(ij)|`

and `A` is called strictly diagonally dominant matrix, if `A_(ii)>sum_(i!=j)^()|A_(ij)|`

`A=[[-3,0,0],[0,-2,0],[0,0,-1]]`

`Row 1:|a_(11)|=|-3|=3,+|a_(12)|+|a_(13)|=+|0|+|0|=0`

 `3 >= 0?` yes

`Row 2:|a_(22)|=|-2|=2,+|a_(21)|+|a_(23)|=+|0|+|0|=0`

`2 >= 0?` yes

`Row 3:|a_(33)|=|-1|=1,+|a_(31)|+|a_(32)|=+|0|+|0|=0`

`1 >= 0?` yes

So, given matrix is Diagonally Dominant