-5/2a,2/9a²b²,-7c/12ab³.2/9-3a,a-1/a²-9.4/3abc²与1/2ab².

-5/2a,2/9a²b²,-7c/12ab³.2/9-3a,a-1/a²-9.4/3abc²与1/2ab².
-5/2a,2/9a²b²,-7c/12ab³.
2/9-3a,a-1/a²-9.
4/3abc²与1/2ab².

-5/2a,2/9a²b²,-7c/12ab³.2/9-3a,a-1/a²-9.4/3abc²与1/2ab².
-5/2a,2/9a²b²,-7c/12ab³.
-5/(2a)=-5*18ab³/(2a*18ab³)=-90ab³/(36a²b³)
2/(9a²b²)=2*2b/(9a²b²*2b)=4b/(36a²b³)
-7c/(12ab³)=-7c*3a/(12ab³*3a)=-21ac/(36a²b³)
2/9-3a,a-1/a²-9.
2/(9-3a)=2*(-1)*(a+3)/((9-3a)*(-1)*(a+3))=(-2a-6)/(3a²-27)
(a-1)/(a²-9)=(a-1)*3/((a²-9)*3)=(3a-3)/(3a²-27)
4/3abc²与1/2ab².
4/(3abc²)=4*2b/(3abc²*2b)=8b/(6ab²c²)
1/(2ab²)=1*3c²/(2ab²*3c²)=3c²/(6ab²c²)