18d^4-45d^3+36d^2
18=2(3)^2
45=5(3)^2
36=(2)^2*(3)^2
Number common factor (18, 45, 36)=(3)^2=9
Variable common factor: d^2
Common factor: 9d^2
9d^2 [18d^4 / (9d^2) - 45d^3 / (9d^2) + 36d^2 / (9d^2) ]=
9d^2 [2d^(4-2) - 5d^(3-2) + 4 ]=
9d^2 (2d^2-5d+4)
Answer: 9d^2 (2d^2-5d+4)