Tính nhanh: 1,-1/2+1/4+2/8-11/77 2,2/5+5/4+(-2/5+5/4)-5/2

2 câu trả lời

1,

-12+14+28-1177

=-24+14+14-17

=-24+(14+14)-17

=-24+24-17

=0-17

=-17

2,

25+54+(-25+54)-52

=25+54-25+54-52

=(25-25)+(54+54)-52

=0+52-52

=0+(52-52)

=0

 

1)-12+14+28-1177

=(-12+14)+28-1177

 =((-1).22.2+14)+28-1177

=(-24+14)+28-1177

=(-14+28)-1177

=((-1).24.2+28)-1177

=(-28+28)-1177

=0-1177

=-1177

2)25+54+(-25+54)-52

=25+54-25+54-52

=(25-25)+54+54-52

=0+54+54-52

=(54+54)-52

=104-52

=52-52

`= 0