câu D là 108 ko phải 1084 đâu nha

723×542:1084=361.5

310×11×5:39×24=10492.30769

24.5-310:39=100-310/39=3590/39 

tick nếu đúng nha

5

78125

531441

alo 

b: \(1024:2^5+140:\left(38+2^5\right)+2\cdot3^2-7^{23}:7^{21}\)

\(=1024:32+140:\left(38+32\right)+2\cdot9-7^2\)

=32+140:70+18-49

=50-49+2

=1+2

=3

c: \(100:\left\lbrace300:\left\lbrack450-\left(4\cdot5^3-2^3\cdot25\right)\right\rbrack\right\rbrace\)

\(=100:\left\lbrace300:\left\lbrack450-\left(4\cdot125-8\cdot25\right)\right\rbrack\right\rbrace\)

\(=100:\left\lbrace300:\left\lbrack450-\left(500-200\right)\right\rbrack\right\rbrace\)

=100:{300:[450-300]}

=100:{300:150}

=100:2

=50

a: 2A=2^2+2^3+...+2^21

=>A=2^21-2

b: B=2+2^2+...+2^100

=>2B=2^2+2^3+...+2^101

=>B=2^101-2

c: C=3+3^2+...+3^10

=>3C=3^2+3^3+...+3^11

=>2C=3^11-3

=>C=(3^11-3)/2

`A = 2 + 2^2 + ... + 2^20`

`=> 2A = 2^2 + 2^3 + ... +2^21`

`=> 2A-A = (2^2 + 2^3 + ... + 2^21) - (2 + 2^2 + ...  +2^20)`

`=> A      = 2^21 - 2`

`B = 2 + 2^2 + ... + 2^99 + 2^100`

`=>2B = 2^2 + 2^3 + ... + 2^100 + 2^101`

`=> 2B-B = (2^2 + 2^3 + ... + 2^101)- (2 + 2^2 + ... + 2^100)`

`=> B      = 2^101 - 2`

`C = 3 + 3^2 +  .... + 3^10`

`=>3C = 3^2 + 3^3 + ... +3^11`

`=>3C - C = (3^2 + 3^3 + ... +3^11) - (3 + 3^2 +  .... + 3^10)`

`=> 2C     = 3^11 - 3`

`=>  C      = (3^11 - 3)/2

\(27.3^{x-5}=3^{10}\\ \Rightarrow3^3.3^{x-5}=3^{10}\\ \Rightarrow3^{x-2}=3^{10}\\ \Rightarrow x-2=10\\ \Rightarrow x=12\)

thank you