15(x-y)^7除以5/6(x-y)^2=25/2(x-y)^5
(-3a^2-9a^3b+12a^4b^2)除以(-3a^2)=1+3ab+4(a^2)(b^2)=(4ab+1)(1-ab)
16(2m-n)^(p+2)除以[-4(2m-n)^(p-1)]=-4(2m-n)^3
15(x-y)^7除以5/6(x-y)^2=25/2(x-y)^5
(-3a^2-9a^3b+12a^4b^2)除以(-3a^2)=1+3ab+4(a^2)(b^2)=(4ab+1)(1-ab)
16(2m-n)^(p+2)除以[-4(2m-n)^(p-1)]=-4(2m-n)^3