1+2+3+4=5+6+7+8+9+10
=(1+9)+(2+8)+(3+7)+(4+6)+(5+10)
= 10+10+10+10+10+15
= 55
=(1+9)+(2+8)+(3+7)+(4+6)+5+10
=10+10+10+10+10+5
=55
=(1+9)+(2+8)+(3+7)+(4+6)+(5+10)
=10+10+10+10+15
=55
số số hạng là :
(10-1):1+1=10 (số)
Tổng là:
(10+1).10:2=55
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
= ( 1 + 9 ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 5 + 10
= 10 + 10 + 10 + 10 + 5 + 10
= 10 x 4 + 5 + 10
= 40 + 5 + 10
= 45 + 10
= 55
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 =
( 1 + 9 ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 10 + 5 =
10 + 10 + 10 + 10 + 10 + 5 =
55
= ( 1 + 9 ) + ( 2 + 8 ) + (3 + 7 ) + ( 4 + 6 ) + 5 + 10
= 10 + 10 + 10 + 10 + 10 + 5
= 55
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
= 3 + 3 + 4 + 5 + 6 +7 + 8 + 9 + 10
= 6 + 4 + 5 + 6 + 7 + 8+ 9 + 10
= 10 + 5 + 6 + 7 + 8 + 9 10
= 15 + 6 + 7 + 8 + 9 + 10
= 21 + 7 + 8 + 9 + 10
= 28 + 8 + 9 + 10
= 36 + 9 + 10
= 45 + 10
= 55
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
= (1 + 9) + (2 + 8) + (3 + 7) + (4 + 6) + 10 + 5
= 10 + 10 + 10 + 10 + 5
= 10 x 5 + 5
= 50 + 5
= 55
k cho mik nha
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10
=( 1 + 9 ) + ( 2 + 8) + ( 3 + 7) + ( 4 + 6 ) + 5 + 10
= 10 + 10 + 10 + 10 + 15
= 55
1+2+3+4+5+6+7+8+9+10=[1+9]+[2+8]+[3+7]+[4+6]+5+10=10+10+10+10+15=55
1+2+3+4+5+6+7+8+9+10
=(1+9)+(2+8)+(3+7)+(4+6)+(5+10)
=10+10+10+10+10+15
=55
1+2+3+4+5+6+7+8+9+10 =(9+1)+(8+2)+(7+3)+(6+4)+(10+5) =10+10+10+10+15 =55