tinh nhanh 55-50+50-45+45-40+40-35+35-30+30-25+25-20 giup minh nh
2 câu trả lời
* Đáp án : 35
* Giải thích các bước giải :
55-50+50-45+45-40+40-35+35-30+30-25+25-20
=(55-50)+(50-45)+(45-40)+(40-35)+(35-30)+(30-25)+(25-20)
=5+5+5+5+5+5+5
=5×7
=35
55−50+50−45+45−40+40−35+35−30+30−25+25−20
=55+(−50+50)+(−45+45)+(−40+40)+(−35+35)+(−30+30)+(−25+25)−20
=55+0+0+0+0+0+0−20
=55−20
=35
