1)4/9-5/12=1/36
2)3/8-4/9=-5/72
3)1/36:(-5/72)=-2/5
-2/5=-0,4
()+10+100=13+2+7+10+100=120+12
(n+1)³-n³=n³+3n²+3n+1-n³=3n²+3n+1=3n(n+1)+1
3∦3n(n+1)+1
((a+b)³=a³+3a²b+3ab²+b³)