Bài 15:a)$\dfrac{-2}{5}$ $\dfrac{4}{5}$ . x =$\dfrac{3}{5}$b)$\dfrac{-3}{7}$ - $\dfrac{4}{7}$:x = -2Bài 16a) x - $\dfrac{10}{3}$ = $\dfrac{7}{15}$ . $\dfrac{3}{5}$b) x \(\dfrac{3}{22...

1

LD

Lâm Đức Khoa

6 tháng 2 2021

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S

shin

6 tháng 2 2021

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

tìm x :a, x . $\dfrac{-5}{8}$ = $\dfrac{15}{32}$ b, $\dfrac{3}{10}$ : x =$\dfrac{-9}{20}$c, $\dfrac{-1}{4}$ x + $\dfrac{4}{5}$ =$\dfrac{3}{4}$ d, $\dfrac{-7}{8}$ + $\dfrac{2}{3}$ :x...

MN

Minh Ngọc 5D - Tuệ Minh1G

25 tháng 3 2023

Bài 4: tìm x:a) $\dfrac{4}{3}$ + (1,25 - x) = 2,25b) $\dfrac{17}{6}$ - (x - $\dfrac{7}{6}$ ) = $\dfrac{7}{4}$c) 4 - (2x + 1) = 3 - $\dfrac{1}{3}$bài 15:a) ($\dfrac{-2}{3}$)9 : x = ($\dfrac{-2}{3}$)b) x : ($\dfrac{4}{9}$)5 = ($\dfrac{4}{9}$)4c) (x + 4)3 = -125d) (10 - 5x)3 = 64e) (4x + 5)2 = 81Bài 16:a) 4 - $1\dfrac{2}{5}$ - $\dfrac{8}{3}$b) -0,6 - $\dfrac{-4}{9}$ - $\dfrac{16}{15}$c) $-\dfrac{15}{4}$ . ($\dfrac{-7}{15}$) . ($-2\dfrac{2}{5}$Gi ải gấp giúp...

4

NK

Ng KimAnhh

25 tháng 3 2023

a, $x\cdot\dfrac{-5}{8}=\dfrac{15}{32}$

$x=\dfrac{15}{32}:\dfrac{-5}{8}$

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

b, $\dfrac{3}{10}:x=\dfrac{-9}{20}$

$x=\dfrac{3}{10}:\dfrac{-9}{20}$

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

c, $\dfrac{-1}{4}x+\dfrac{4}{5}=\dfrac{3}{4}$

$\dfrac{-1}{4}x=\dfrac{3}{4}-\dfrac{4}{5}$

$\dfrac{-1}{4}x=-\dfrac{1}{20}$

$x=-\dfrac{1}{20}:\dfrac{-1}{4}$

$x=\dfrac{1}{5}$

d, $\dfrac{-7}{8}+\dfrac{2}{3}:x=\dfrac{3}{5}\cdot\dfrac{-5}{12}$

$\dfrac{-7}{8}+\dfrac{2}{3}:x=-\dfrac{1}{4}$

$\dfrac{2}{3}:x=-\dfrac{1}{4}+\dfrac{-7}{8}$

$\dfrac{2}{3}:x=\dfrac{5}{8}$

$x=\dfrac{2}{3}:\dfrac{5}{8}$

$x=\dfrac{16}{15}$

#YVA6

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Y

YangSu

25 tháng 3 2023

$a,x.\dfrac{-5}{8}=\dfrac{15}{32}$

$\Leftrightarrow x=\dfrac{15}{32}:\dfrac{-5}{8}$

$\Leftrightarrow x=\dfrac{15}{32}.\dfrac{-8}{5}$

$\Leftrightarrow x=-\dfrac{3}{4}$

$b,\dfrac{3}{10}:x=-\dfrac{9}{20}$

$\Leftrightarrow x=\dfrac{3}{10}:\dfrac{-9}{20}$

$\Leftrightarrow x=\dfrac{3}{10}.\dfrac{-20}{9}$

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

$c,-\dfrac{1}{4}x+\dfrac{4}{5}=\dfrac{3}{4}$

$\Leftrightarrow-\dfrac{1}{4}x=\dfrac{3}{4}-\dfrac{4}{5}$

$\Leftrightarrow-\dfrac{1}{4}x=-\dfrac{1}{20}$

$\Leftrightarrow x=-\dfrac{1}{20}\times\left(-4\right)$

$\Leftrightarrow x=\dfrac{1}{5}$

$d,-\dfrac{7}{8}+\dfrac{2}{3}:x=\dfrac{3}{5}.\dfrac{-5}{12}$

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

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

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

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

$\Leftrightarrow x=\dfrac{16}{15}$

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HT

Ha Thù

11 tháng 9 2023

#Toán lớp 7

3

VN

Võ Ngọc Phương

VIP

11 tháng 9 2023

Bài 4:

a) $\dfrac{4}{3}+\left(1,25-x\right)=2,25$

$1,25-x=2,25-\dfrac{4}{3}=\dfrac{9}{4}-\dfrac{4}{3}$

$1,25-x=\dfrac{11}{12}$

$x=1,25-\dfrac{11}{12}=\dfrac{5}{4}-\dfrac{11}{12}$

$x=\dfrac{1}{3}$

b) $\dfrac{17}{6}-\left(x-\dfrac{7}{6}\right)=\dfrac{7}{4}$

$x-\dfrac{7}{6}=\dfrac{17}{6}-\dfrac{7}{4}=\dfrac{34}{12}-\dfrac{21}{12}$

$x-\dfrac{7}{6}=\dfrac{13}{12}$

$x=\dfrac{13}{12}+\dfrac{7}{6}=\dfrac{13}{12}+\dfrac{14}{12}$

$x=\dfrac{27}{12}=\dfrac{9}{4}$

c) $4-\left(2x+1\right)=3-\dfrac{1}{3}=\dfrac{9}{3}-\dfrac{1}{3}$

$4-\left(2x+1\right)=\dfrac{8}{3}$

$2x+1=\dfrac{8}{3}+4=\dfrac{8}{3}+\dfrac{12}{3}$

$2x+1=\dfrac{20}{3}$

$2x=\dfrac{20}{3}-1=\dfrac{20}{3}-\dfrac{3}{3}$

$2x=\dfrac{17}{3}$

$x=\dfrac{17}{3}.\dfrac{1}{2}=\dfrac{17}{6}$

Bài 15:

a) $\left(\dfrac{-2}{3}\right)^9:x=\dfrac{-2}{3}$

$x=\left(\dfrac{-2}{3}\right)^9:\dfrac{-2}{3}=\left(\dfrac{-2}{3}\right)^{9-1}$

$=>x=\left(\dfrac{-2}{3}\right)^8$

b) $x:\left(\dfrac{4}{9}\right)^5=\left(\dfrac{4}{9}\right)^4$

$x=\left(\dfrac{4}{9}\right)^4.\left(\dfrac{4}{9}\right)^5=\left(\dfrac{4}{9}\right)^{4+5}$

$=>x=\left(\dfrac{4}{9}\right)^9$

c) $\left(x+4\right)^3=-125$

$\left(x+4\right)^3=\left(-5\right)^3$

$=>x+4=-5$

$x=-5-4$

$=>x=-9$

d) $\left(10-5x\right)^3=64$

$\left(10-5x\right)^3=4^3$

$=>10-5x=4$

$5x=10-4$

$5x=6$

$=>x=\dfrac{6}{5}$

e) $\left(4x+5\right)^2=81$

$\Leftrightarrow\left[{}\begin{matrix}\left(4x+5\right)^2=\left(-9\right)^2\\\left(4x+5\right)^2=9^2\end{matrix}\right.$

$\Leftrightarrow\left[{}\begin{matrix}4x+5=-9\\4x+5=9\end{matrix}\right.$

$\Leftrightarrow\left[{}\begin{matrix}4x=-14\\4x=4\end{matrix}\right.$

$\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-14}{4}\\x=1\end{matrix}\right.$

Bài 16:

a) $4-1\dfrac{2}{5}-\dfrac{8}{3}$

$=4-\dfrac{7}{5}-\dfrac{8}{3}$

$=\dfrac{60-21-40}{15}=\dfrac{-1}{15}$

b) $-0,6-\dfrac{-4}{9}-\dfrac{16}{15}$

$=\dfrac{-3}{5}+\dfrac{4}{9}-\dfrac{16}{15}$

$=\dfrac{\left(-27\right)+20-48}{45}=\dfrac{-55}{45}=\dfrac{-11}{9}$

c) $-\dfrac{15}{4}.\left(\dfrac{-7}{15}\right).\left(-2\dfrac{2}{5}\right)$

$=\dfrac{7}{4}.\dfrac{-12}{5}$

$=\dfrac{-21}{5}$

$#Wendy.Dang$

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HT

Ha Thù

11 tháng 9 2023

Uh, chừa sau k dám học muộn nx

Tìm x:a) $\dfrac{-3}{7}$.x=$\dfrac{3}{56}$.$\dfrac{28}{9}$b) x-$\dfrac{3}{16}$=$\dfrac{7}{15}$:$\dfrac{3}{5}$c) $\dfrac{2}{5}$+$\dfrac{1}{5}$.x=$\dfrac{5}{6}$d) $\dfrac{3}{4}$x-$\dfrac{2}{5}$x=$\dfrac{3}{7}$.$\dfrac{1}{6}$+$\dfrac{5}{7}$.$\dfrac{1}{6}$*Lưu ý: Trình bày chi tiết kết...

AT

Anh Tuấn Đào

7 tháng 4 2022

bài 1 : a) $\dfrac{2}{5}+\dfrac{3}{8}=$ b)$\dfrac{7}{6}-\dfrac{2}{3}=$ c)$\dfrac{5}{9}\times6$ d)$\dfrac{8}{5}:\dfrac{4}{7}=$bài 2:a) $\dfrac{4}{5}+$ x =$\dfrac{5}{6}$ b)x : $\dfrac{7}{10}=5$bài 3 : hai xe ô tô chở được tất cả 16 tấn 8 tạ hàng . Xe ô tô thứ nhất chở được nhiều hơn xe ô tô thứ hai 2 tấn 6 tạ hàng . Hỏi mỗi xe chở được bao nhiêu tạ hàng bài 4 :145 $\times$ 69 + 22 x 145 +145...

2

TC

TV Cuber

7 tháng 4 2022

a)$x=\left(\dfrac{3}{56}\cdot\dfrac{28}{9}\right):\dfrac{-3}{7}=\dfrac{1}{6}:\dfrac{-3}{7}=-\dfrac{7}{18}$

b)$x=\left(\dfrac{7}{15}\cdot\dfrac{5}{3}\right)+\dfrac{3}{16}=\dfrac{7}{9}+\dfrac{3}{16}=\dfrac{139}{144}$

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TC

TV Cuber

7 tháng 4 2022

c)$x=\left(\dfrac{5}{6}-\dfrac{2}{5}\right).5=\dfrac{13}{6}$

d)$=>x\left(\dfrac{3}{4}-\dfrac{2}{5}\right)=\dfrac{1}{6}\cdot\left(\dfrac{3}{7}+\dfrac{5}{7}\right)$

$x\cdot\dfrac{7}{20}=\dfrac{4}{21}=>x=\dfrac{4}{21}\cdot\dfrac{20}{7}=\dfrac{80}{147}$

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NK

Nguyễn Khánh Linh

8 tháng 5 2022

Tìm x: a) $\dfrac{11}{12}$ - ($\dfrac{2}{5}$ + $\dfrac{3}{4}$x) $\dfrac{2}{3}$ b) $\dfrac{-2}{5}$ + $\dfrac{5}{3}$ . ($\dfrac{3}{2}$ - $\dfrac{4}{15}$x) = $\dfrac{-7}{6}$ c) $\dfrac{1}{2}$ + $\dfrac{3}{4}$x...

#Toán lớp 4

3

TC

TV Cuber

8 tháng 5 2022

bài 1

a)$=\dfrac{16}{40}+\dfrac{15}{40}=\dfrac{31}{40}$

b)$=\dfrac{7}{6}-\dfrac{4}{6}=\dfrac{3}{6}=\dfrac{1}{2}$

c)$=\dfrac{30}{9}=\dfrac{10}{3}$

d)$=\dfrac{8}{5}\times\dfrac{7}{4}=\dfrac{56}{20}=\dfrac{14}{5}$

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TC

TV Cuber

8 tháng 5 2022

bài 2

a)$x=\dfrac{5}{6}-\dfrac{4}{5}=\dfrac{25}{30}-\dfrac{24}{30}=\dfrac{1}{30}$

b)$x=5\times\dfrac{10}{7}=\dfrac{50}{7}$

bài 4 :

145 $\times$ 69 + 22 x 145 +145 x 8 + 145

$=145\times\left(69+22+8+1\right)=145\times100=14500$

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LP

Lê Phương Linh

29 tháng 9 2023

#Toán lớp 7

2

KT

『Kuroba ム Tsuki Ryoo ︵²ᵏ⁷』

29 tháng 9 2023

`#3107`

a)

$\dfrac{11}{12}-\left(\dfrac{2}{5}+\dfrac{3}{4}x\right)=\dfrac{2}{3}?\\ \Rightarrow\dfrac{2}{5}+\dfrac{3}{4}x=\dfrac{11}{12}-\dfrac{2}{3}\\ \Rightarrow\dfrac{2}{5}+\dfrac{3}{4}x=\dfrac{1}{4}\\ \Rightarrow\dfrac{3}{4}x=\dfrac{1}{4}-\dfrac{2}{5}\\ \Rightarrow\dfrac{3}{4}x=-\dfrac{3}{20}\\ \Rightarrow x=-\dfrac{3}{20}\div\dfrac{3}{4}\\ \Rightarrow x=-\dfrac{1}{5}$

Vậy, $x=-\dfrac{1}{5}$

b)

$\dfrac{-2}{5}+\dfrac{5}{3}\cdot\left(\dfrac{3}{2}-\dfrac{4}{15}x\right)=\dfrac{-7}{6}\\ \Rightarrow\dfrac{5}{3}\cdot\left(\dfrac{3}{2}-\dfrac{4}{15}x\right)=\dfrac{-7}{6}-\dfrac{-2}{5}\\ \Rightarrow\dfrac{5}{3}\cdot\left(\dfrac{3}{2}-\dfrac{4}{15}x\right)=-\dfrac{23}{30}\\ \Rightarrow\dfrac{3}{2}-\dfrac{4}{15}x=-\dfrac{23}{30}\div\dfrac{5}{3}\\ \Rightarrow\dfrac{3}{2}-\dfrac{4}{15}x=-\dfrac{23}{50}\\ \Rightarrow\dfrac{4}{15}x=\dfrac{3}{2}-\left(-\dfrac{23}{50}\right)\\ \Rightarrow\dfrac{4}{15}x=\dfrac{49}{25}\\ \Rightarrow x=\dfrac{147}{20}$

Vậy, $x=\dfrac{147}{20}$

c)

$\dfrac{1}{2}+\dfrac{3}{4}x=\dfrac{1}{4}\\ \Rightarrow\dfrac{3}{4}x=\dfrac{1}{4}-\dfrac{1}{2}\\ \Rightarrow\dfrac{3}{4}x=-\dfrac{1}{4}\\ \Rightarrow x=-\dfrac{1}{4}\div\dfrac{3}{4}\\ \Rightarrow x=-\dfrac{1}{3}$

Vậy, $x=-\dfrac{1}{3}.$

$#Emyeu1aithatroi...$

TM

Trịnh Minh Trí

29 tháng 9 2023

(2/5 + 3/4 . x)= 11/12 -2/3

(2/5 +3/4 . x)= 1/4

3/4 . x = 1/4 - 2/5

3/4 . x = -3/20

x = -3/20 : 3/4

x = -1/5

Vậy .....

tính bằng cách thuận tiện nhất a, $\dfrac{5}{13}$x$\dfrac{4}{15}$x13= b, ($\dfrac{3}{7}$+$\dfrac{5}{2}$)x$\dfrac{7}{5}$= ...

3T

37-Trần Quang Tuấn-4D

8 tháng 3 2022

#Toán lớp 4

2

I

ILoveMath

8 tháng 3 2022

$a,\dfrac{5}{13}\times\dfrac{4}{15}\times13=\dfrac{5\times4\times13}{13\times5\times3}=\dfrac{4}{3}\\ b,\left(\dfrac{3}{7}+\dfrac{5}{2}\right)\times\dfrac{7}{5}=\dfrac{3}{7}\times\dfrac{7}{5}+\dfrac{5}{2}\times\dfrac{7}{5}=\dfrac{3}{5}+\dfrac{7}{2}=\dfrac{6}{10}+\dfrac{35}{10}=\dfrac{41}{10}\\ c,\dfrac{1}{5}\times\dfrac{11}{18}+\dfrac{11}{18}\times\dfrac{3}{5}=\dfrac{11}{18}\times\left(\dfrac{1}{5}+\dfrac{3}{5}\right)=\dfrac{11}{18}\times\dfrac{4}{5}=\dfrac{22}{45}$

NH

Nguyễn Hà Khanh

8 tháng 3 2022

a, 4/3 b, 41/10 c,22/45

Tính bằng cách thuận tiện nhất:a) 60 x...

PB

Phùng Bảo Châu

18 tháng 3 2022