=(102-101)+(100-99)+....+(2-1)

=1+1+...+1(51 số hạng)

=51

102 - 101 + 100 - 99 + 98 - 97 + ... + 4 - 3 + 2 - 1

= ( 102 - 101 ) + ( 100 - 99 ) + ( 98 - 97 ) + ... + ( 4 - 3 ) + ( 2 - 1 )

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

= 1 . 51

= 51

Khó zóa . Hok tốt

1 + 1 = 2 nhé

2 nhé

mk mình tk lại

1+2=3

k nha

Tổng các chữ số của số A là :

        [ ( 2015 - 1 ): 1 + 1 - 1 ] : 2  * ( 2 + 2015 ) + 1 = 2031120

Do 2031120 \(⋮\)9 \(\Rightarrow\)A \(⋮\)9

Có lẽ là 8

Cảm ơn

= 128/256 + 64/256 + 32/256 + 16/256 + 8/256 + 4/256 + 2/256 + 1/256 

= 255/256

q​uy đ​ồ​ng mẫ​u số​ bạ​n nhé​. Mẫ​u số chung = 256

12+14+18+164+1128+1256" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:15.82px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; overflow-wrap:normal; padding:1px 0px; position:relative; white-space:nowrap; word-break:break-word; word-spacing:normal" class="MathJax_CHTML mjx-chtml">12+14+18+164+1128+1256" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:15.82px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; overflow-wrap:normal; padding:1px 0px; position:relative; white-space:nowrap; word-break:break-word; word-spacing:normal" class="MathJax_CHTML mjx-chtml">12+14+18+164+1128+1256

121+122+123+124+125+126+127+128" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:15.82px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; overflow-wrap:normal; padding:1px 0px; position:relative; white-space:nowrap; word-break:break-word; word-spacing:normal" class="MathJax_CHTML mjx-chtml">121+122+123+124+125+126+127+128

121+122+123+124+125+126+127+128)" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:15.82px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; overflow-wrap:normal; padding:1px 0px; position:relative; white-space:nowrap; word-break:break-word; word-spacing:normal" class="MathJax_CHTML mjx-chtml">121+122+123+124+125+126+127+128)

121+122+123+124+125+126+127" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:15.82px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; overflow-wrap:normal; padding:1px 0px; position:relative; white-space:nowrap; word-break:break-word; word-spacing:normal" class="MathJax_CHTML mjx-chtml">121+122+123+124+125+126+127

121+122+123+124+125+126+127)−(121+122+123+124+125+126+127+128)" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-table; float:none; font-size:15.82px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; overflow-wrap:normal; padding:1px 0px; position:relative; white-space:nowrap; word-break:break-word; word-spacing:normal" class="MathJax_CHTML mjx-chtml">121+122+123+124+125+126+127)−(121+122+123+124+125+126+127+128)128=1−1256=255256" role="presentation" style="border:0px; box-sizing:border-box; direction:ltr; display:inline-block; float:none; font-size:15.82px; line-height:0; margin:0px; max-height:none; max-width:none; min-height:0px; min-width:0px; overflow-wrap:normal; padding:1px 0px; position:relative; white-space:nowrap; word-break:break-word; word-spacing:normal" class="MathJax_CHTML mjx-chtml">A=1−128=1−1256=255256

100-99+98-97+96-95+94-93+92-91+.........+2-1=50

\(=\left(100-99\right)+\left(98-97\right)+...+\left(2-1\right)\)

 \(=1+1+...+1\)

  \(=1.\left(\frac{100}{2}\right)\)

\(=1.50\)

\(=50\)

100-99=1;98-97=1;.....;2-1

như vậy là có 50 cặp ; 50 cặp đó đều có hiệu là 1

1+1+1+1+....+1=50 nha

19

k nha

1+3+5+10=19

1+3+5+10=19 nha bn