Số?a) $\dfrac{2}{5}=\dfrac{2\times3}{5\times3}=\dfrac{?}{?}$ $\dfrac{4}{7}=\dfrac{4\times2}{7\times2}=\dfrac{?}{?}$ \(\dfrac{13}{54}=\dfrac{13\times3}{54\times3}...

ML

Minh Lệ

23 tháng 8 2023

Số?a) $\dfrac{2}{5}=\dfrac{2\times3}{5\times3}=\dfrac{?}{?}$ $\dfrac{4}{7}=\dfrac{4\times2}{7\times2}=\dfrac{?}{?}$ $\dfrac{13}{54}=\dfrac{13\times3}{54\times3}=\dfrac{?}{?}$b) $\dfrac{8}{20}=\dfrac{8:4}{20:4}=\dfrac{?}{?}$ $\dfrac{10}{16}=\dfrac{10:2}{16:2}=\dfrac{?}{?}$ ...

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#Toán lớp 4

1

GL

Gia Linh

24 tháng 8 2023

a) $\dfrac{2}{5}=\dfrac{2\times3}{5\times3}=\dfrac{6}{15}=\dfrac{2}{5}$

$\dfrac{4}{7}=\dfrac{4\times2}{7\times2}=\dfrac{8}{14}=\dfrac{4}{7}$

$\dfrac{13}{54}=\dfrac{13\times3}{54\times3}=\dfrac{39}{162}=\dfrac{13}{54}$

b) $\dfrac{8}{20}=\dfrac{8:4}{20:4}=\dfrac{2}{5}$

$\dfrac{10}{16}=\dfrac{10:2}{16:2}=\dfrac{5}{8}$

$\dfrac{25}{65}=\dfrac{25:5}{65:5}=\dfrac{5}{13}$

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TT

Trịnh Thị Thảo Nhi

26 tháng 7 2017

Tính a, 4$\times\left(-\dfrac{1}{2}\right)^3-2\times\left(-\dfrac{1}{2}\right)^2+3\times\left(-\dfrac{1}{2}\right)+1$ b, $\dfrac{4^6\times9^5+6^9\times120}{-8^4\times3^{12}+6^{11}}$ c, $\dfrac{155-\dfrac{10}{7}-\dfrac{5}{11}+\dfrac{5}{23}}{403-\dfrac{26}{7}-\dfrac{13}{11}+\dfrac{12}{23}}+\dfrac{\dfrac{3}{5}+\dfrac{3}{13}-0,9}{\dfrac{7}{91}+0,2-\dfrac{3}{10}}$ d,$\dfrac{30\times4^7\times3^{29}-5\times14^5\times2^{12}}{54\times6^{14}\times9^7-12\times8^5\times7^5}$ ...

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#Toán lớp 6

2

KL

Khánh Linh

26 tháng 7 2017

a, $4\times\left(-\dfrac{1}{2}\right)^3-2\times\left(-\dfrac{1}{2}\right)^2+3\times\left(-\dfrac{1}{2}\right)+1$

$=\left(-\dfrac{1}{2}\right)\left[\left(4\times-\dfrac{1}{2}\right)-\left(2\times-\dfrac{1}{2}\right)+3\right]+1$

$=\left(-\dfrac{1}{2}\right)\left(-2+1+3\right)+1$

$=\left(-\dfrac{1}{2}\right)2+1$

$=-1+1$

$=0$

@Trịnh Thị Thảo Nhi

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C

chugialinh

29 tháng 4 2018

a, $4\times(-12)3-2\times(-12)2+3\times(-12)+14\times(-12)3-2\times(-12)2+3\times(-12)+1$

$=(-12)[(4\times-12)-(2\times-12)+3]+1=(-12)[(4\times-12)-(2\times-12)+3]+1$

$=(-12)(-2+1+3)+1=(-12)(-2+1+3)+1$

$=(-12)2+1=(-12)2+1$

$=-1+1=-1+1$

$=0=0$

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PN

Phạm Ngọc Châu

17 tháng 10 2017

Tính giá trị của mỗi phân số sau:

$E=\dfrac{11\times3^{29}-\left(3^2\right)^{15}}{2\times3^{14}\times2\times3^{14}}$

$G=\dfrac{5\times3^{11}+4\times3^{12}}{3^9\times5^2-3^0\times2^3}$

$H=\dfrac{\left(3\times4\times2^{16}\right)^2}{11\times2^{13}\times4^{11}-16^9}$

#Toán lớp 6

1

TM

Trần Minh Hoàng

17 tháng 10 2017

$E=\dfrac{11.3^{29}-3^{2^{15}}}{2.3^{14}.2.3^{14}}$

$=\dfrac{11.3-3^{30}}{2^2}=\dfrac{33-3^{30}}{4}$

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N

NguyễnĐứcanh

26 tháng 7 2021

$\dfrac{4^{10}\times9^6+3^{12}\times8^5}{6^{13}\times4-2^{16}\times3^{12}}$

$\dfrac{2^4\times2^6}{\left(2^5\right)^2}-\dfrac{2^5\times15^3}{6^3\times10^2}$

$\dfrac{\left(-2\right)^{10}\times3^{31}+2^{40}\times\left(-3\right)^6}{\left(-2\right)^{11}\times\left(-3\right)^{31}+2^{41}\times3^6}$

giải chi tiết giúp mình nhé

#Toán lớp 7

1

TC

Trên con đường thành công không có....

26 tháng 7 2021

undefined

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DN

Đỗ Ngọc Hải

15 tháng 7 2017

a)$\left(\dfrac{17}{10}+7-8,7\right)\div\left(\dfrac{23}{4}-\dfrac{11}{4}+\dfrac{9}{25}\right)\times\left(12,98\times0,25\right)+12,5$

b)$1\dfrac{2}{24}\times5\dfrac{2}{5}\times2\times3\dfrac{7}{9}\times2\times\dfrac{2}{17}$

#Toán lớp 6

1

NL

Nguyễn Lê Phước Thịnh

21 tháng 5 2022

a: $=\left(\dfrac{17}{10}+\dfrac{70}{10}-\dfrac{87}{10}\right):\left(\dfrac{23}{4}-\dfrac{11}{4}+\dfrac{9}{25}\right)\cdot\left(12,98\cdot0,25\right)+12,5$

$=0:\left(3+\dfrac{9}{25}\right)\cdot\left(12,98+0,25\right)+12,5$

=12,5

b: $=\dfrac{13}{12}\cdot\dfrac{27}{5}\cdot2\cdot\dfrac{34}{9}\cdot2\cdot\dfrac{2}{17}$

$=\dfrac{13}{12}\cdot2\cdot\dfrac{27}{5}\cdot\dfrac{34}{9}\cdot\dfrac{4}{17}$

$=\dfrac{13}{6}\cdot\dfrac{27}{5}\cdot\dfrac{8}{9}=\dfrac{8}{6}\cdot3\cdot\dfrac{13}{5}=4\cdot\dfrac{13}{5}=\dfrac{52}{5}$

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TN

Thế Nam

4 tháng 11 2023

$\dfrac{2}{1\times2\times3}+\dfrac{2}{2\times3\times4}+\dfrac{2}{3\times4\times5}+...+\dfrac{2}{48\times49\times50}$

#Toán lớp 5

2

T

Toru

4 tháng 11 2023

$\dfrac{2}{1\times2\times3}+\dfrac{2}{2\times3\times4}+\dfrac{2}{3\times4\times5}+...+\dfrac{2}{48\times49\times50}$

$=\dfrac{1}{1\times2}-\dfrac{1}{2\times3}+\dfrac{1}{2\times3}-\dfrac{1}{3\times4}+\dfrac{1}{3\times4}-\dfrac{1}{4\times5}+...+\dfrac{1}{48\times49}-\dfrac{1}{49\times50}$

$=\dfrac{1}{1\times2}-\dfrac{1}{49\times50}$

$=\dfrac{1}{2}-\dfrac{1}{2450}$

$=\dfrac{612}{1225}$

$\text{#}Toru$

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DD

Đỗ Danh Bằng

VIP

4 tháng 11 2023

1/2 - 1/49 x50

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LN

linh nguyen ngoc

19 tháng 7 2018

Tính giá trị biểu thức:

B=$\dfrac{5}{1\times2}+\dfrac{13}{2\times3}+\dfrac{25}{3\times4}+\dfrac{41}{4\times5}+...+\dfrac{181}{9\times10}$

#Toán lớp 7

1

PC

Phan Công Bằng

19 tháng 7 2018

$B=\dfrac{5}{1.2}+\dfrac{13}{2.3}+\dfrac{25}{3.4}+\dfrac{41}{4.5}+...+\dfrac{181}{9.10}$

$=\left(\dfrac{1}{1.2}+\dfrac{4}{1.2}\right)+\left(\dfrac{1}{2.3}+\dfrac{12}{2.3}\right)+\left(\dfrac{1}{3.4}+\dfrac{24}{3.4}\right)+...+\left(\dfrac{1}{9.10}+\dfrac{180}{9.10}\right)$

$\left(\dfrac{1}{1.2}+\dfrac{1}{2.3}+...+\dfrac{1}{9.10}\right)+\left(\dfrac{4}{1.2}+\dfrac{12}{2.3}+...+\dfrac{180}{9.10}\right)$

$=\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{9}-\dfrac{1}{10}\right)+\left(2+2+...+2\right)$

$=1-\dfrac{1}{10}+\left(2.9\right)$

$=1-\dfrac{1}{10}+18$

$=\dfrac{9}{10}+18$

$=18\dfrac{9}{10}$

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DA

Đào Anh Thư ^_~

23 tháng 7 2023

$\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+...+\dfrac{1}{98\times99}+\dfrac{1}{99\times100}$

$\dfrac{2}{11\times13}+\dfrac{2}{13\times15}+...+\dfrac{2}{19\times21}+\dfrac{2}{21\times23}$

#Toán lớp 5

2

AD

@DanHee

23 tháng 7 2023

$1,\\ =\dfrac{2-1}{1\times2}+\dfrac{3-2}{2\times3}+\dfrac{4-3}{3\times4}+\dfrac{5-4}{4\times5}+.....+\dfrac{99-98}{98\times99}+\dfrac{100-99}{99\times100}\\ =1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+....+\dfrac{1}{98}-\dfrac{1}{99}+\dfrac{1}{99}-\dfrac{1}{100}\\ =1-\dfrac{1}{100}=\dfrac{100-1}{100}=\dfrac{99}{100}$

$2,=\dfrac{13-11}{11\times13}+\dfrac{15-13}{13\times15}+....+\dfrac{21-19}{19\times21}+\dfrac{23-21}{21\times23}\\ =\dfrac{1}{11}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{15}+....+\dfrac{1}{19}-\dfrac{1}{21}+\dfrac{1}{21}-\dfrac{1}{23}\\ =\dfrac{1}{11}-\dfrac{1}{23}\\ =\dfrac{23-11}{11\times23}=\dfrac{12}{253}$

@seven

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NL

Nguyễn Lê Phước Thịnh

23 tháng 7 2023

a: 1/1*2+1/2*3+...+1/99*100

=1-1/2+1/2-1/3+...+1/99-1/100

=1-1/100

=99/100

b: 2/11*13+2/13*15+...+2/21*23
=1/11-1/13+1/13-1/15+...+1/21-1/23

=1/11-1/23

=12/253