B = 26 + 115 + 74 - 15

B = (26 + 74) + (115 - 15)

B = 100 + 100

B = 200

C = 45.27 + 27.53 + 54

C = 27(45 + 53) + 54

C = 27.92 + 54   tự tính nốt đi

Cho mình hỏi bài này yêu câu j z

B = 26 + 115 + 74 - 15

   = (26 + 74) + (115 - 15)

   = 100+100

   = 200

C = 45 x 27 + 27 x 53 + 54

    = 45 x 27 + 27 x 53 + 27 x 2

    = 27 x ( 45 + 53 + 2 )

    = 27 x 100

    = 2700

D = 2018 + 2018 x 113 - 2018 x 14

   = 2018 x ( 1 + 113 - 14 )

   = 2018 x 100

   = 201 800

D = 2018 + 2018 x 113 - 2018 x 14

D = 2018 x ( 1+113-14)

D = 2018 x 100 = 201800 .

k nha!

\(D=2018+2018.113-2018.14\)

\(D=2018.\left(1+113-14\right)\)

\(D=2018.\left(114-14\right)\)

\(D=2018.100\)

\(D=201800\)

A = 47 x 36 + 64 x 47 + 15

A= 47 x ( 64 + 36 ) + 15 = 47 x 100 + 15 = 4700 + 15 = 4715

vậy A= 4715

B= 27+35 + 65 + 73+ 75

B= (27+ 73) + ( 35 + 65) +75

B= 100 +100 +75 = 275

vậy B= 275

C= 37 +37 x 15 +37 x 84 

C= 37 x ( 1+15 +84 )= 37 x 100 = 3700

 vậy C= 3700

D = 1/20x21  +  1/21x22    +    1/22x23    +    1/23x24

D= 1/20   -   1/21   +    1/21  -  1/22   + 1/22   -   1/23  +   1/23   -    1/24

D= 1/20 -1/24 = 1/120 vậy D= 1/120

E= 1/1x2   +  1/2x3 + ...... + 1/49x50

E= 1/1  -   1/2    +    1/2  -   1/3  +...... + 1/49   -   1/50

E = 1 - 1/50 = 49/50 

vậy E= 49/50

 CHÚC HOK TOT

b,(6,27+158,61-27)x(4,5x2-90:10)

=(6,27+158,61-27)x(9-9)

=(6,27+158,61-27)x0

=0

a,\(\left(\frac{1}{2018}-\frac{1}{2017}+\frac{1}{2016}\right)x\left(\frac{5}{6}-\frac{1}{2}-\frac{1}{3}\right)\)

\(=\left(\frac{1}{2018}-\frac{1}{2017}+\frac{1}{2016}\right)x0\)

\(=0\)

a, \(\left(\frac{1}{2018}-\frac{1}{2017}+\frac{1}{2016}\right)\cdot\left(\frac{5}{6}-\frac{1}{2}-\frac{1}{3}\right)\)

\(=\left(\frac{1}{2018}-\frac{1}{2017}+\frac{1}{2016}\right)\cdot\left(\frac{5-3-2}{6}\right)\)

\(=\left(\frac{1}{2018}-\frac{1}{2017}+\frac{1}{2016}\right)\cdot0=0\)

b, \(\left(6,27+158,61-27\right)\cdot\left(4,5\cdot2-90\div10\right)\)

\(=\left(6,27+158,61-27\right)\cdot\left(9-9\right)\)

\(=\left(6,27+158,61-27\right)\cdot0=0\)

\(\left(x-1\right)^x=10^{11}\)

\(\Leftrightarrow\left(x-1\right)^x=\left(11-1\right)^{11}\)

\(\Rightarrow x=11\)

(x  -  1)^x = 10¹¹

=> x - 1 = 10

=> x  = 11

vậy_

     \(\left(X-1\right)^x=10^{11}\)

      \(=>X=11\)  

a. 54 x 113 + 45 x 113 + 113

= 113 x (54 + 45 + 1)

= 113 x 100 = 11300

Vậy giá trị cần tìmlaf: 11300

b. 54 x 47 - 47 x 53 - 20 - 27

= 54 x 47 - 47 x 53 - (20 + 27)

= 54 x 47 - 47 x 53 - 47

= 47 x (54 - 53 - 1)

= 47 x 0 = 0

Vậy giá trị cần tìm là: 0

\(a,54\times113+45\times113+113\\ =113\times\left(54+45+1\right)\\ =113\times100=11300\)

\(b,54\times47-47\times53-20-27\\ =54\times47-47\times53-47\\ =47\times\left(54-53-1\right)\\ =47\times0=0\)

a 11300

 b  0

S=3/2^0+3/2^1+....+3/2^2018

S=3/2.(2/2^0+2/2^1+....+2^2018)

đặt B=2/2^0+2/2^1+....+2^2018

2B=2.(2/2^0+2/2^1+....+2^2018)

2B=1+2/2^0+...+2/2^2017

2B-B=(1+2/2^0+...+2/2^2017)-(2/2^0+2/2^1+....+2^2018)

B=1-2^2018

S=3/2.1-2^2018=3/2^2018

B=2^2018-1 nha mink làm lộn

a) 6*1235*20-5*235*24 = 120(1235-235)=120.1000=120000

b) =[145*99+145*1]-[143101*1]=145*[99+1]-145*[101-1]=145*100-143*100=100*[145-143]=100*2=200

\(2A=\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+\frac{2}{9.11}=\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}\)

        \(=1-\frac{1}{11}=\frac{10}{11}\)

\(\Rightarrow A=\frac{5}{11}\)

\(2B=\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{2017.2019}=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{2017}-\frac{1}{2019}\)

        \(=1-\frac{1}{2019}=\frac{2018}{2019}\Rightarrow B=\frac{1009}{2019}\)

\(\frac{2}{7}C=\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{2017.2019}=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{2017}-\frac{1}{2019}\)

           \(=1-\frac{1}{2019}=\frac{2018}{2019}\Rightarrow C=\frac{2018}{2019}:\frac{2}{7}=\frac{7063}{2019}\)