a) $\dfrac{-2}{15}\times x=\dfrac{-2}{7}$ b) $\dfrac{7}{-5}\times x=-3$ c) $-\dfrac{4}{9}x=\dfrac{1}{2}$ d) \(\dfr...

1

NL

Nguyễn Lê Phước Thịnh

31 tháng 12 2022

a: =>x*2/15=2/7

=>x=2/7:2/15=2/7*15/2=15/7

b: x=3:7/5=15/7

c: x=-1/2:4/9=-1/2*9/4=-9/8

d: x=-8/3:3/8=-64/9

g: =>4/11x=2/5+1/3=6/15+5/15=11/15

=>x=11/15:4/11=121/60

l: =>1/4:x=1-3/2=-1/2

=>x=-1/4:1/2=-1/4*2=-1/2

k: =>x:7=-1/3+5/2=-2/6+15/6=13/6

=>x=91/6

a. $\dfrac{2}{15}+3$ b. $2-\dfrac{7}{4}$ c. $\dfrac{17}{6}-\dfrac{11}{12}\times6$ d.$\dfrac{14}{17}:7-\dfrac{15}{34}$bài 3: a. x : 23 =146 b. x $\times$ 38 =4066 c.787 +x $\times$ 67 =2658 bài 4: tổng hai số là số bé nhất có bốn chữ số khách nhau .Số bé bằng $\dfrac{1}{5}$số lớn . Tìm hai số đó ?bài 5 :ba bạn xuân, hạ , thu cắt được 180 bông hoa .Hạ cắt được nhiều hơn xuân 9 bông...

NK

Nguyễn Khánh Linh

9 tháng 5 2022

#Toán lớp 4

4

O

★彡✿ทợท彡★

9 tháng 5 2022

B1 :

a) $\dfrac{2}{15}+3=\dfrac{2}{15}+\dfrac{15}{5}=\dfrac{17}{5}$

b) $2-\dfrac{7}{4}=\dfrac{8}{4}-\dfrac{7}{4}=\dfrac{1}{4}$

c) $\dfrac{17}{6}-\dfrac{11}{12}\times6=\dfrac{17}{6}-\dfrac{11}{2}=-\dfrac{8}{3}$

d) $\dfrac{14}{17}:7-\dfrac{15}{34}=\dfrac{2}{17}-\dfrac{5}{34}=\dfrac{4}{34}-\dfrac{5}{34}=-\dfrac{1}{34}$

B3 :

$x:23=146$

$x=146\times23$

$x=3358$

b) $x\times38=4066$

$x=4066:38$

$x=107$

c) $787+x\times67=2658$

$x\times67=2658-787$

$x\times67=1871$

$x=1871:67$

$x=\dfrac{1871}{67}$

YA

You are my sunshine

9 tháng 5 2022

từng bài thôi

Tìm $x$ biết:$a.x=\dfrac{1}{5}+\dfrac{-3}{7}$ $b.\dfrac{3}{5}-\dfrac{4}{7}\div x=\dfrac{-9}{10}$ $c.x-\left(\dfrac{-3}{4}\right)=\dfrac{-2}{3}-\dfrac{1}{2}$ ...

CH

Chử Hải Yến

3 tháng 4 2022

Số?a) $\dfrac{3}{5}=\dfrac{3\times4}{5\times4}=\dfrac{?}{?}$ $\dfrac{2}{7}=\dfrac{2\times?}{7\times3}=\dfrac{?}{?}$b) $\dfrac{9}{12}=\dfrac{9:3}{12:3}=\dfrac{?}{?}$ ...

1

Y

YangSu

3 tháng 4 2022

$a,x=\dfrac{1}{5}+\dfrac{-3}{7}$

$x=\dfrac{7}{35}+\dfrac{-15}{35}$

$x=-\dfrac{8}{35}$

$b,\dfrac{3}{5}-\dfrac{4}{7}:x=\dfrac{-9}{10}$

$\dfrac{4}{7}:x=\dfrac{3}{5}-\dfrac{-9}{10}$

$\dfrac{4}{7}:x=\dfrac{3}{2}$

$x=\dfrac{4}{7}:\dfrac{3}{2}$

$x=\dfrac{4}{7}\times\dfrac{2}{3}$

$x=\dfrac{8}{21}$

$c,x-\left(\dfrac{-3}{4}\right)=\dfrac{-2}{3}-\dfrac{1}{2}$

$x+\dfrac{3}{4}=\dfrac{-4}{6}-\dfrac{3}{6}$

$x+\dfrac{3}{4}=-\dfrac{7}{6}$

$x=-\dfrac{7}{6}-\dfrac{3}{4}$

$x=-\dfrac{23}{12}$

$d,\dfrac{-5}{9}-x=\dfrac{1}{3}+\dfrac{7}{18}$

$\dfrac{-5}{9}-x=\dfrac{6}{18}+\dfrac{7}{18}$

$\dfrac{-5}{9}-x=\dfrac{13}{18}$

$x=\dfrac{-5}{9}-\dfrac{13}{18}$

$x=\dfrac{-10}{18}-\dfrac{13}{18}$

$x=-\dfrac{23}{18}$

Đúng(2)

D

datcoder

CTVVIP

9 tháng 10 2023

#Toán lớp 4

2

NG

Người Già

CTVVIP

9 tháng 10 2023

a) $\dfrac{12}{20}$
b)$\dfrac{6}{21}$
c)$\dfrac{3}{4}$
d) 6 ; $\dfrac{3}{4}$

1. tìm x thuộc z biết $\dfrac{x}{-12}$=$\dfrac{-3}{2}$ 2 tính a,$\dfrac{-7}{9}\times\dfrac{6}{11}+\dfrac{-2}{9}$ b,$\dfrac{-4}{7}:2=$ c,115-...

KT

『Kuroba ム Tsuki Ryoo ︵²ᵏ⁷』

9 tháng 10 2023

loading...

Đúng(2)

BT

bùi thị ngọc linh

8 tháng 5 2017

2

TD

Tứ Diệp Thảo My My

8 tháng 5 2017

1,

x =( -12 . ( -3) ) : 2

x = 18

2,

a, -7/9 . 6/11 + (-2/9) = -14/33 + (-2/9) = -64/99

b, -4/7 : 2 = -4/7 . 1/2 = -2/7

c, 115 - (24 - 5. 3) = 115 - ( 24 - 15) = 115 - 9 = 106

d,= -3/7. (5/9 + 4/9) + 17/7 = -3/7 . 1 +17/7 = -3/7 . 17/7 = -51/49

e, ??? mình cx k biết

S

Sáng

8 tháng 5 2017

Lời giải:

$\dfrac{x}{-12}=\dfrac{-3}{2}$

$\Rightarrow2x=-12.\left(-3\right)$

$\Rightarrow2x=36$

$\Rightarrow x=18$

HQ

Hạ Quỳnh

20 tháng 12 2020

Bài 2:Tìm x...

1

NL

Nguyễn Lê Phước Thịnh

20 tháng 12 2020

a) Ta có: $\dfrac{1}{7}+x=-\dfrac{2}{3}$

$\Leftrightarrow x=-\dfrac{2}{3}-\dfrac{1}{7}=\dfrac{-14}{21}-\dfrac{3}{21}$

hay $x=-\dfrac{17}{21}$

Vậy: $x=-\dfrac{17}{21}$

b) Ta có: $\dfrac{-2}{3}:x=\dfrac{-5}{6}$

$\Leftrightarrow x=\dfrac{-2}{3}:\dfrac{-5}{6}=\dfrac{-2}{3}\cdot\dfrac{6}{-5}=\dfrac{-12}{-15}=\dfrac{4}{5}$

Vậy: $x=\dfrac{4}{5}$

c) Ta có: $\left(\dfrac{3}{5}-2x\right)\cdot\dfrac{5}{8}=1$

$\Leftrightarrow\left(\dfrac{3}{5}-2x\right)=1:\dfrac{5}{8}=\dfrac{8}{5}$

$\Leftrightarrow-2x=\dfrac{8}{5}-\dfrac{3}{5}=1$

hay $x=-\dfrac{1}{2}$

Vậy: $x=-\dfrac{1}{2}$

d) Ta có: $\dfrac{3}{4}+\dfrac{2}{5}x=\dfrac{29}{60}$

$\Leftrightarrow x\cdot\dfrac{2}{5}=\dfrac{29}{60}-\dfrac{3}{4}=\dfrac{29}{60}-\dfrac{45}{60}=\dfrac{-16}{60}=\dfrac{-4}{15}$

hay $x=\dfrac{-4}{15}:\dfrac{2}{5}=\dfrac{-4}{15}\cdot\dfrac{5}{2}=\dfrac{-20}{30}=-\dfrac{2}{3}$

Vậy: $x=-\dfrac{2}{3}$

e) Ta có: $\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}$

$\Leftrightarrow\dfrac{1}{4}:x=\dfrac{2}{5}-\dfrac{3}{4}=\dfrac{8}{20}-\dfrac{15}{20}=\dfrac{-7}{20}$

hay $x=-\dfrac{1}{4}:\dfrac{7}{20}=\dfrac{-1}{4}\cdot\dfrac{20}{7}=\dfrac{-20}{28}=\dfrac{-5}{7}$

Vậy: $x=-\dfrac{5}{7}$

f) Ta có: $\dfrac{11}{12}-\left(\dfrac{2}{5}+x\right)=\dfrac{2}{3}$

$\Leftrightarrow-x+\dfrac{11}{12}-\dfrac{2}{5}-\dfrac{2}{3}=0$

$\Leftrightarrow-x+\dfrac{55}{60}-\dfrac{24}{60}-\dfrac{40}{60}=0$

$\Leftrightarrow-x-\dfrac{9}{60}=0$

$\Leftrightarrow-x=\dfrac{9}{60}=\dfrac{3}{20}$

hay $x=-\dfrac{3}{20}$

Vậy: $x=-\dfrac{3}{20}$

g) Ta có: $\left|x+\dfrac{1}{3}\right|-4=\dfrac{-1}{2}$

$\Leftrightarrow\left|x+\dfrac{1}{3}\right|=\dfrac{-1}{2}+4=\dfrac{-1}{2}+\dfrac{8}{2}=\dfrac{7}{2}$

$\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{3}=\dfrac{7}{2}\\x+\dfrac{1}{3}=-\dfrac{7}{2}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{7}{2}-\dfrac{1}{3}=\dfrac{21}{6}-\dfrac{2}{6}=\dfrac{19}{6}\\x=-\dfrac{7}{2}-\dfrac{1}{3}=\dfrac{-21}{6}-\dfrac{2}{6}=\dfrac{-23}{6}\end{matrix}\right.$

Vậy: $x\in\left\{\dfrac{19}{6};-\dfrac{23}{6}\right\}$

HQ

Hạ Quỳnh

20 tháng 12 2020

cảm ơn cậu cutee gì đó ơi nha

DD

Đinh Diệp

2 tháng 7 2018

thực hiện phép tính

a)$\dfrac{x^3}{x^2+1975}\times\dfrac{2x+1954}{x+1}+\dfrac{x^3}{x^2+1975}\times\dfrac{21-x}{x+1}$

b)$\dfrac{19x+8}{x-7}\times\dfrac{5x-9}{x+1945}+\dfrac{19x+8}{x^2+1945}\times\dfrac{1x-2}{x-7}$

c) $\dfrac{x+1}{x^2-2x-8}\times\dfrac{4-x}{x^2+x}$

#Toán lớp 8

1

AT

Aki Tsuki

3 tháng 7 2018

a/ $\dfrac{x^3}{x^2+1975}\cdot\dfrac{2x+1954}{x+1}+\dfrac{x^3}{x^2+1975}\cdot\dfrac{21-x}{x+1}=\dfrac{x^3\left(2x+1954\right)+x^3\left(21-x\right)}{\left(x^2+1975\right)\left(x+1\right)}=\dfrac{2x^4+1954x^3+21x^3-x^4}{\left(x^2+1975\right)\left(x+1\right)}=\dfrac{x^4+1975x^3}{\left(x^2+1975\right)\left(x+1\right)}$

b/ $\dfrac{19x+8}{x-7}\cdot\dfrac{5x-9}{x+1945}+\dfrac{19x+8}{x^2+1945}\cdot\dfrac{x-2}{x-7}=\dfrac{\left(19x+8\right)\left(5x-9\right)+\left(19x+8\right)\left(x-2\right)}{\left(x-7\right)\left(x+1945\right)}=\dfrac{\left(19x+8\right)\left(5x-9+x-2\right)}{\left(x-7\right)\left(x+1945\right)}=\dfrac{114x^2-209x+40x-88}{\left(x-7\right)\left(x+1945\right)}=\dfrac{114x^2-169x-88}{x^2+1938x-13615}$

c/ $\dfrac{x+1}{x^2-2x-8}\cdot\dfrac{4-x}{x^2+x}=\dfrac{\left(x+1\right)\left(4-x\right)}{x\left[x^2-4x+2x-8\right]\left(x+1\right)}=-\dfrac{x-4}{x\left(x-4\right)+2\left(x-4\right)}=-\dfrac{x-4}{\left(x-4\right)\left(x+2\right)}=-\dfrac{1}{x+2}$

NQ

Nguyễn Quốc Toàn

25 tháng 3 2018

$A.\dfrac{-15}{28}x\dfrac{7}{25}\\ B.\dfrac{-5}{14}x\dfrac{7}{-3}\\ C.\dfrac{-1}{5}-\dfrac{7}{15}x\dfrac{9}{35}\\ D.\dfrac{-3}{4}-(\dfrac{-1}{2})^2\\ E.\dfrac{-4}{5}-\dfrac{-4}{5}x\dfrac{15}{16}\\F.(\dfrac{3}{4}+\dfrac{-7}{2})x(\dfrac{2}{11}+\dfrac{12}{22})$

1

NL

Nguyễn Lê Phước Thịnh

26 tháng 6 2022

a: $A=\dfrac{-7}{28}\cdot\dfrac{15}{25}=\dfrac{-1}{4}\cdot\dfrac{3}{5}=\dfrac{-3}{20}$

b: $B=\dfrac{-5\cdot7}{14\cdot\left(-3\right)}=\dfrac{35}{42}=\dfrac{5}{6}$

c: $C=\dfrac{-1}{5}-\dfrac{1}{5}\cdot\dfrac{3}{5}=\dfrac{-1}{5}-\dfrac{3}{25}=\dfrac{-8}{25}$

d: $D=\dfrac{-3}{4}-\dfrac{1}{4}=-1$

e: $E=\dfrac{-4}{5}\left(1-\dfrac{15}{16}\right)=\dfrac{-4}{5}\cdot\dfrac{1}{16}=\dfrac{-1}{20}$

f: $F=\dfrac{6-7}{4}\cdot\dfrac{4+12}{22}=\dfrac{-1}{4}\cdot\dfrac{8}{11}=\dfrac{-2}{11}$

CT

Cao Tùng Lâm

26 tháng 1 2022

A = $\dfrac{-19}{9}\times\dfrac{1}{2}-\dfrac{4}{11}\times\dfrac{-11}{9}+\left(-\dfrac{2}{3}\right)$

B = $\left(-\dfrac{15}{6}\right)\div\dfrac{-1}{2}+\dfrac{7}{-12}-\dfrac{1}{3}\times\dfrac{-11}{2}$

C = $\dfrac{3}{4}\times\left(-8\right)-\dfrac{1}{3}\times\dfrac{-7}{2}-\dfrac{5}{18}$

2

MH

Minh Hiếu

26 tháng 1 2022

$A=\dfrac{-19}{9}.\dfrac{1}{2}-\dfrac{4}{11}.\dfrac{-11}{9}+\left(-\dfrac{2}{3}\right)=-\dfrac{23}{18}$

$B=\left(-\dfrac{15}{6}\right):\dfrac{-1}{2}+\dfrac{7}{-12}-\dfrac{1}{3}.\dfrac{-11}{2}=\dfrac{25}{4}$

$C=\dfrac{3}{4}.\left(-8\right)-\dfrac{1}{3}.\dfrac{-7}{2}-\dfrac{5}{18}=-\dfrac{46}{9}$

NL

Nguyễn Lê Phước Thịnh

26 tháng 1 2022

$A=\dfrac{-19}{18}+\dfrac{4}{9}-\dfrac{2}{3}=\dfrac{-19}{18}+\dfrac{8}{18}-\dfrac{12}{18}=\dfrac{-23}{18}$

$B=\dfrac{-5}{2}\cdot\dfrac{-2}{1}-\dfrac{7}{12}+\dfrac{11}{6}=\dfrac{5\cdot12-7+22}{12}=\dfrac{75}{12}=\dfrac{25}{4}$

Tính:a) $\dfrac{2}{5}\times\dfrac{3}{8}\times\dfrac{3}{4}$ b) $\dfrac{1}{3}\times\dfrac{1}{6}\times\dfrac{1}{9}$c) $\dfrac{3}{4}:\dfrac{1}{5}:\dfrac{7}{8}$ ...

D

datcoder

CTVVIP

31 tháng 10 2023

#Toán lớp 4

1

HQ

Hà Quang Minh

Giáo viên

27 tháng 11 2023

a) $\frac{2}{5} \times \frac{3}{8} \times \frac{3}{4} = \frac{{2 \times 3 \times 3}}{{5 \times 8 \times 4}} = \frac{{18}}{{160}} = \frac{9}{{80}}$

b) $\frac{1}{3} \times \frac{1}{6} \times \frac{1}{9} = \frac{{1 \times 1 \times 1}}{{3 \times 6 \times 9}} = \frac{1}{{162}}$

c) $\frac{3}{4}:\frac{1}{5}:\frac{7}{8} = \frac{3}{4} \times \frac{5}{1} \times \frac{8}{7} = \frac{{3 \times 5 \times 8}}{{4 \times 1 \times 7}} = \frac{{120}}{{28}} = \frac{{30}}{7}$

d) $\frac{3}{5}:\frac{1}{5}:\frac{3}{8} = \frac{3}{5} \times \frac{5}{1} \times \frac{8}{3} = \frac{{3 \times 5 \times 8}}{{5 \times 1 \times 3}} = 8$