Question

20 -18 + 18 - 17 + 16 - 15 + ...+ 4 - 3 + 2 - 1

Toán lp 3 giúp vssss

Answer 1

20 - 18 + 18 - 17 + 16 - 15 +...+ 4 - 3 + 2 - 1

= 11

Answer 2

20 -18 + 18 - 17 + 16 - 15 + ...+ 4 - 3 + 2 - 1

=(20-18) + (18-17) + ( 16-15) + ...+ (4-3) + (2-1)

=2+1+1+1+....+1+1

=2+1x9

=2+9

=11

Answer 3

20-18+18-17+16-15+...+4-3+2-1

=(20-18)+(18-17)+(16-15)+(14-13)+(12-11)+(10-9)+(8-7)+(6-5)+(4-3)+(2-1)

=2+1+1+1+1+1+1+1+1+1

=11

Answer 4

mk viết nhầm đề nha là 20-19 + 18 - 17 + 16 - 15 + ...+ 4 - 3 + 2 - 1