1−2−3+4+5−6−7+8+...+21−22−23+24+25

= (1 - 2 - 3 + 4) + (5 - 6 - 7 + 8) + ... + (21 - 22 - 23 + 24) + 25=(1−2−3+4)+(5−6−7+8)+...+(21−22−23+24)+25

= 0 + 0 + ... + 0 + 25=0+0+...+0+25

= 25

Đặt A=1 + 2 + 2²+ 2³+ 2⁴ +... + 2⁹⁹ + 2¹⁰⁰

=>2A=2 + 2²+ 2³+ 2⁴ +... + 2⁹⁹ + 2¹⁰⁰+2¹⁰¹

=>2A-A=(2 + 2²+ 2³+ 2⁴ +... + 2⁹⁹ + 2¹⁰⁰+2¹⁰¹)-(1 + 2 + 2²+ 2³+ 2⁴ +... + 2⁹⁹ + 2¹⁰⁰)

=>A=2¹⁰¹-1

1 - 2 - 3 + 4 + 5 - 6 - 7 + 8 + ... + 21 - 22 - 23 + 24 + 25.

=(1 - 2 - 3 + 4) + (5 - 6 - 7 + 8) + ......+ ( 21 - 22 - 23 + 24)+25

= 0+0+0+......+0+25

=0+25

=25

~HT~

@Jennie

mk nghĩ ko cần giải thik đâu

vì mk ghép các cặp lại để ra kq bằng 0

sau đó cộng thêm 25

là ra kq 25

~HT

#Jennie

\(A=1+2+2^2+2^3+2^4+...+2^{99}+2^{100}\)

\(\Rightarrow2A=2+2^2+2^3+2^4+2^5+...+2^{100}+2^{101}\)

\(\Rightarrow2A-A=2^{101}-1\)

\(\Leftrightarrow A=2^{101}-1\)

Đặt biểu thức là A

ta có 2A-A=2^101-1

TA có 13-13*1+10-10= 13- 13+10-10=0+0=0

(10*11+12*13+14*15+...+22*23+24*25)*0=0

* là dấu x nhe bạn 

thick minh nha

( 10 x 11 + 12 x 13 + 14 x 15 + ... + 22 x 23 + 24 x 25) x ( 13 - 13 x 1 + 10 -10)

= ( 10 x 11 + 12 x 13 + 14 x 15 + ... + 22 x 23 + 24 x 25) x 0

= 0

 k cho anh nha !!!!!!!!!!!!!!!! : học lớp 5 rùi

cậu tham khảo linh này nhé :

olm.vn/hoi-dap/question/976586.html

chúc cậu học tốt 

\(\frac{2016^{26}+2016^{24}+...+2016^4+2016^2}{2016^{24}+2016^{22}+...+2016^2+1}\) \(=\frac{2016^2.\left(2016^{24}+2016^{22}+...+2016^2+1\right)}{2016^{24}+2016^{22}+...+2016^2+1}\)

\(=\frac{2016^2}{1}=2016^2\)

Ta có: \(A=1+\dfrac{1}{8}+\dfrac{1}{24}+\dfrac{1}{48}+\dfrac{1}{80}+\dfrac{1}{120}\)

\(\Leftrightarrow2A=2+\dfrac{2}{2\cdot4}+\dfrac{2}{4\cdot6}+\dfrac{2}{6\cdot8}+\dfrac{2}{8\cdot10}+\dfrac{2}{10\cdot12}\)

\(\Leftrightarrow2A=2+\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{10}+\dfrac{1}{10}-\dfrac{1}{12}\)

\(\Leftrightarrow2A=2+\dfrac{1}{2}-\dfrac{1}{12}\)

\(\Leftrightarrow2A=\dfrac{24}{12}+\dfrac{6}{12}-\dfrac{1}{12}\)

\(\Leftrightarrow2A=\dfrac{29}{12}\)

hay \(A=\dfrac{29}{24}\)