1) Resolva os sistemas lineares usando a regra de Cramer:
a) x-y=3
2x+3y=6
b) 4x-5y=1
-2x+y=-11
c) 2x+3y+6z=15
-x+4y+z=24
3x-y+7z=-7
d) 2x-3y-z=0
-2x+y+2z=-9
4x+2y+z=1
