2a³+8a²-ab+c
a= - 3
2·(-3)³+8·(-3)²-(-3)b+c =2·(-27)+8·9+3b+c=-27+72+9b+c=3b + c + 18
a=2
2·2³+8·2²-2b+c =2·8+8·4-2b+c=16+32-2b+c=- 2b + c + 48
+_______________
2a³+8a²-ab+c
a= - 3
2·(-3)³+8·(-3)²-(-3)b+c =2·(-27)+8·9+3b+c=-27+72+9b+c=3b + c + 18
a=2
2·2³+8·2²-2b+c =2·8+8·4-2b+c=16+32-2b+c=- 2b + c + 48
+_______________