1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+................+200 

Ss hạng là: ( 200 - 1 ) : 1 + 1 = 200 

Tổng là : ( 1 + 200 ) . 200 : 2 =  20100

số số hạng là :

( 200 - 1 ) : 1 + 1 = 200

Tổng là :

( 200 + 1 ) x 200 : 2 = 20100

đáp số : 20100

X = ( 1+10 ) * 10 / 2 = 11 * 10 / 2 = 110 / 2 = 55

X= (2+20) * 10 /2 = 110

X= (1+19)*10/2= 100

1+2+3+4+5+6+7+8+9+10= (10+1)X10 : 2 = 55

2+4+6+8+10+12+14+16+18+20 = (20+2)x10 : 2 = 110

1+3+5+7+9+11+13+15+17+19 = (19+1) x 10 : 2 = 100

(1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20 ) -1-5-9-3=

= ( 1 + 20 ) x 20 : 2 - 1 - 5 - 9 - 3 

= 210 - 1 - 5 - 9 - 3 

= 192

hok tốt

bn rảnh ghê ha

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20-1-5-9-3=192

=12345830

6402373705728000

=210 k nha

turbo pascal là ra ngay

(1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20)*(21*4+6-84)=330

330 nha

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21=231

trả lời:

=231

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= 1+(2-3)+(4-5)+(6-7)+........+(18-19)+20

= 1+(-1)+(-1)+(-1)+........+(-1)+20

= 1+(-9)+20

= 12

Tính: 1+2-3+4-5+6-7+8-9+10-11+12-13+14-15+16-17+18-19+20 = ?

= 1+(2-3)+(4-5)+(6-7)+........+(18-19)+20

= 1+(-1)+(-1)+(-1)+........+(-1)+20

= 1+(-9)+20

= 12

nhé !