chs thek ko bt nhucj har bn Error

\(a, -5+6=6-5=1 b, -5+12=12-5=7\)

\( (-11).77 - 23.11 + (-29) \)

\(=11.(-77)-23.11+(-29)\)

\(=11.[(-77)-23]+(-29)\)

\(=11.(-100)+(-29)\)

= -1100 + (-29)

= -(1100+29)=-1071

khet day 

hong thay chu

:)?

2,5dm=25cm

dt hình chữ nhật la:

25x18=450(\(cm^2\))

450cm2=4,5\(dm^2\)