1: =29-16-3*2=13-6=7

2: =35-12+(-14)-2

=23-16=7

3: =4*3125-32:16

=12500-2

=12498

4: =-452+67-75+452=-8

5: =18+99*18-3^5-2^5

=1800-275

=1525

300

465 

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

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

\(\Rightarrow A-\dfrac{A}{3}=\dfrac{2A}{3}=\left(\dfrac{1}{3}+\dfrac{1}{3^2}+\dfrac{1}{3^3}+...+\dfrac{1}{3^{99}}\right)-\left(\dfrac{1}{3^2}+\dfrac{1}{3^3}+\dfrac{1}{3^4}+...+\dfrac{1}{3^{100}}\right)\)

\(\Rightarrow\dfrac{2A}{3}=\left(\dfrac{1}{3^2}-\dfrac{1}{3^2}\right)+\left(\dfrac{1}{3^3}-\dfrac{1}{3^3}\right)+...+\left(\dfrac{1}{3^{99}}-\dfrac{1}{3^{99}}\right)+\left(\dfrac{1}{3}-\dfrac{1}{3^{100}}\right)=\dfrac{1}{3}-\dfrac{1}{3^{100}}\)

\(\Rightarrow2A=3\cdot\left(\dfrac{1}{3}-\dfrac{1}{3^{100}}\right)\)

\(\Rightarrow\text{A}=\dfrac{1-\dfrac{1}{3^{99}}}{2}\)

\(\Rightarrow A=\dfrac{1}{2}-\dfrac{1}{2.3^{99}}< \dfrac{1}{2}\)

Tính các tổng sau:

1, S=1-2+3_4+..+25-26

S =-1+3-5+7-...-53+55                       ( có 28 số hạng )

   = (-1+3)+(-5+7)+...+(-53+55)         ( có 28:2=14 nhóm )

   = 2+2+...+2

    = 2 . 14

     = 28

Á nhầm rùi xl bn nha

a: \(61\cdot45+61\cdot23-68\cdot51\)

\(=61\left(45+23\right)-68\cdot51\)

\(=68\cdot61-68\cdot51\)

\(=68\left(61-51\right)=68\cdot10=680\)

b: \(3\cdot5^2-\left(75-4\cdot2^3\right)\)

\(=75-75+4\cdot8\)

\(=4\cdot8=32\)

c: \(36:\left\{2^2\cdot5-\left[30-\left(5-1\right)^2\right]\right\}\)

\(=\dfrac{36}{20-30+4^2}\)

\(=\dfrac{36}{-10+16}=\dfrac{36}{6}=6\)

d: \(\left(12\cdot49-3\cdot2^2\cdot7^2\right):\left(2020\cdot2021\right)\)

\(=\dfrac{\left(12\cdot49-12\cdot49\right)}{2020\cdot2021}=0\)

a, 68 + 42 x 5 - 625 : 25

  = 68 + 210    -  25

=    278  - 25

=     253

b, 15 x { 37 + 8 + 20 } + 15 x { 13 + 22 }

  = 15 x   65               + 15 x    35

  = 15 x { 65 + 35 }

  = 15 x  100

  =  1500

c, 125 x 56 x 3

   = 7000  x 3 

   =    21000

d, 249 - { 49 - 100 }

  = 249 - 49 + 100

  = 200  + 100

  =  300

e, 1/2 + 1/4 + 1/ 8 + 1/32 + 1/64 + 1/128

   = 1/1 - 1/2 + 1/2 - 1/4 + 1/4 - 1/8 + 1/8 - 1/32 + 1/32 - 1/64 + 1/64 - 1/128

   = 1/1 - 1/128

   =   127/128

A, \(68+42\times5-625:25\)

= 68 +210 - 25

= 278 - 25

= 253

B,\(15\times\left(37+8+20\right)+15\times\left(13+22\right)\)

= \(15\times\left(37+8+20+13+22\right)\)

=\(15\times100\)

= 1500

C,\(125\times56\times3\)

= \(125\times8\times7\times3\)

=  \(1000\times21\)

= 21000

D, 249 - { 49 - 100 }

= 249 - 49 -100

= 200 - 100

= 100

E, \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}\)(mình sửa lại đề chút xíu nha, nó cứ bị sai sai sao ấy)

= \(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+\frac{1}{8}-\frac{1}{16}+\frac{1}{16}-\frac{1}{32}+\frac{1}{32}-\frac{1}{64}+\frac{1}{64}-\frac{1}{128}\) 

= \(1-\frac{1}{128}\)

=\(\frac{128}{128}-\frac{1}{128}\)

= \(\frac{127}{128}\)

má có thực hiện phép tính cx hỏi ngu z bé

ngta ko làm thì hỏi tại sao cứ phải chửi mới đc ý nhở