1, 4z*3 - 8z*2 - 9z+ 18 =0
<=> 4z*2( z - 2 ) - 9( z - 2 ) = 0
<=> ( z - 2 )( 2z - 3)(2z + 3) = 0
+) z - 2 = 0 <=> z = 2
+) 2z - 3 =0 <=> z = 3/2
+) 2z + 3 = 0 <=> z = -3/2
2, z*4 + 4z*3 - 16z -16 =0
<=> z*3(z + 1) - 16(z + 1) =0
<=> (z + 1)(z*3 - 16 ) = 0
+) z + 1 = 0 <=> z = -1
+) z*3 - 16 = 0...