Bài 3: Tìm $x$, biết : a, ( $x$ 2,8 ) : 5 = 0,3 b, ( $x$ $\dfrac{5}{6}$ ) . 2$\dfrac{2}{5}$ - 1$\dfrac{1}{4}$ = 35% c, $\dfrac{1-2x}{2}$ = $\dfrac{-1,5}{3}$ d, 1,4$x$

2

KT

『Kuroba ム Tsuki Ryoo ︵²ᵏ⁷』

11 tháng 4

`#3107.101107`

`3.`

`a,`

`(x + 2,8) \div 5 = 0,3`

$\Rightarrow x+2,8=0,3\cdot5$

$\Rightarrow x+2,8=1,5$

$\Rightarrow x=1,5-2,8$

$\Rightarrow x=-1,3$

Vậy, `x = -1,3`

`b,`

$\left(x+\dfrac{5}{6}\right)\cdot2\dfrac{2}{5}-1\dfrac{1}{4}=35\%$

$\Rightarrow\left(x+\dfrac{5}{6}\right)\cdot\dfrac{12}{5}=0,35+\dfrac{5}{4}$

$\Rightarrow x+\dfrac{5}{6}=\dfrac{2}{3}$

$\Rightarrow x=\dfrac{2}{3}-\dfrac{5}{6}$

$\Rightarrow x=-\dfrac{1}{6}$

Vậy, $x=-\dfrac{1}{6}$

`c,`

$\dfrac{1-2x}{2}=\dfrac{-1,5}{3}\\ \Rightarrow\left(1-2x\right)\cdot3=2\cdot\left(-1,5\right)\\ \Rightarrow1-2x=-3\div3\\ \Rightarrow1-2x=-1\\ \Rightarrow2x=1-\left(-1\right)\\ \Rightarrow2x=2\\ \Rightarrow x=1$

Vậy, `x = 1`

`d,`

`1,4x - x = -8,844`

$\Rightarrow 0,4x = -8,844$

$\Rightarrow x = -8,844 \div 0,4$

$\Rightarrow x = -22,11$

Vậy, `x = -22,11`

`e,`

`x - 5,01 = 7,02 - 2 * 1,5`

$\Rightarrow x - 5,01 = 7,02 - 3$

$\Rightarrow x - 5,01 = 4,02$

$\Rightarrow x = 4,02 + 5,01$

$\Rightarrow x = 9,03$

Vậy, `x = 9,03.`

AH

Akai Haruma

Giáo viên

11 tháng 4

Lời giải:
a. $(x+2,8):5=0,3$

$x+2,8=0,3.5=1,5$

$x=1,5-2,8=-1,3$

b.

$(x+\frac{5}{6}).2\frac{2}{5}-1\frac{1}{4}=35\text{%}=\frac{7}{20}$

$(x+\frac{5}{6}).\frac{12}{5}-\frac{5}{4}=\frac{7}{20}$

$(x+\frac{5}{6}).\frac{12}{5}=\frac{7}{20}+\frac{5}{4}=\frac{8}{5}$

$x+\frac{5}{6}=\frac{8}{5}: \frac{12}{5}=\frac{2}{3}$

$x=\frac{2}{3}-\frac{5}{6}=\frac{-1}{6}$

c.

$\frac{1-2x}{2}=\frac{-1,5}{3}$

$\frac{1}{2}-x=\frac{-1}{2}$

$x=\frac{1}{2}-\frac{-1}{2}=1$

d.

$1,4x-x=-8,844$

$0,4x=-8,844$

$x=-8,844:0,4=-22,11$

e.

$x-5,01=7,02-2.1,5$

$x-5,01=4,02$

$x=4,02+5,01=9,03$

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

NT

Nguyễn Thu Huyền

1 tháng 9 2023

Tìm...

Bài 1 : Thực hiện phép tính:a, $\dfrac{6}{7}.[\left(\dfrac{-7}{5}-\dfrac{3}{2}:\dfrac{-5}{-4}\right)+\left(\dfrac{3}{2}\right)^2]$Bài 2 : Tìm x : a , $\dfrac{2}{3}:x=1,4-\dfrac{12}{5}$b , $\dfrac{x}{5}=\dfrac{5}{6}+\dfrac{-19}{30}$Bài 3 : Lớp 6A có 40 h/s . Cuối năm xếp loại giỏi , khá , TB . Biết số h/s giỏi bằng $\dfrac{1}{4}$số h/s cả lớp . Số h/s khá bằng $\dfrac{3}{5}$số h/s còn lại Tính số h/s giỏi , khá , TB?Bài 4 : Lớp 6B có h/s xếp...

#Toán lớp 7

3

T

Toru

1 tháng 9 2023

$a,3-x=x+1,8$

$\Rightarrow-x-x=1,8-3$

$\Rightarrow-2x=-1,2$

$\Rightarrow x=0,6$

$b,2x-5=7x+35$

$\Rightarrow2x-7x=35+5$

$\Rightarrow-5x=40$

$\Rightarrow x=-8$

$c,2\left(x+10\right)=3\left(x-6\right)$

$\Rightarrow2x+20=3x-18$

$\Rightarrow2x-3x=-18-20$

$\Rightarrow-x=-38$

$\Rightarrow x=38$

$d,8\left(x-\dfrac{3}{8}\right)+1=6\left(\dfrac{1}{6}+x\right)+x$

$\Rightarrow8x-3+1=1+6x+x$

$\Rightarrow8x-3=7x$

$\Rightarrow8x-7x=3$

$\Rightarrow x=3$

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

$\Rightarrow-3x+x=\dfrac{4}{3}-\dfrac{2}{9}$

$\Rightarrow-2x=\dfrac{10}{9}$

$\Rightarrow x=-\dfrac{5}{9}$

Đúng(3)

T

Toru

1 tháng 9 2023

$g,\dfrac{1}{2}x+\dfrac{5}{6}=\dfrac{3}{4}x-\dfrac{1}{2}$

$\Rightarrow\dfrac{1}{2}x-\dfrac{3}{4}x=-\dfrac{1}{2}-\dfrac{5}{6}$

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

$\Rightarrow x=\dfrac{16}{3}$

$h,x-4=\dfrac{5}{6}\left(6-\dfrac{6}{5}x\right)$

$\Rightarrow x-4=5-x$

$\Rightarrow x+x=5+4$

$\Rightarrow2x=9$

$\Rightarrow x=\dfrac{9}{2}$

$k,7x^2-11=6x^2-2$

$\Rightarrow7x^2-6x^2=-2+11$

$\Rightarrow x^2=9\Rightarrow\left[{}\begin{matrix}x=3\\x=-3\end{matrix}\right.$

$m,5\left(x+3\cdot2^3\right)=10^2$

$\Rightarrow5\left(x+24\right)=100$

$\Rightarrow x+24=20$

$\Rightarrow x=-4$

$n,\dfrac{4}{9}-\left(\dfrac{1}{6^2}\right)=\dfrac{2}{3}\left(x-\dfrac{2}{3}\right)^2+\dfrac{5}{12}$

$\Rightarrow\dfrac{2}{3}\left(x-\dfrac{2}{3}\right)^2+\dfrac{5}{12}=\dfrac{4}{9}-\dfrac{1}{36}$

$\Rightarrow\dfrac{2}{3}\left(x-\dfrac{2}{3}\right)^2+\dfrac{5}{12}=\dfrac{5}{12}$

$\Rightarrow\dfrac{2}{3}\left(x-\dfrac{2}{3}\right)^2=0$

$\Rightarrow x-\dfrac{2}{3}=0\Rightarrow x=\dfrac{2}{3}$

#$Urushi\text{☕}$

Đúng(3)

NA

Ngọc Anh

20 tháng 4 2022

1

NL

Nguyễn Lê Phước Thịnh

28 tháng 6 2023

2:

a: =>2/3:x=1,4-2,4=-1

=>x=-2/3

b: =>x/5=25/30-19/30=6/30=1/5

=>x=1

3:

Số học sinh giỏi là 40*1/4=10 bạn

Số học sinh khá là 30*3/5=18 bạn

Số học sinh TB là 30-18=12 bạn

KJ

❖ Khang/GD❄ 『ʈєɑɱ❖Hoàng๖ۣۜGia☆』

28 tháng 2 2022

Tìm x biết:

$a,\left(x-\dfrac{3}{4}\right)+50\%=\dfrac{1}{6}$

$b,\dfrac{1}{2}x-\dfrac{5}{6}x=\dfrac{7}{2}$

$c,\left(4-x\right)\left(3x+5\right)=0$

$d,\dfrac{x}{16}=\dfrac{50}{32}$

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

1

NL

Nguyễn Lê Phước Thịnh

28 tháng 2 2022

a: =>x-3/4=1/6-1/2=1/6-3/6=-2/6=-1/3

=>x=-1/3+3/4=-4/12+9/12=5/12

b: =>x(1/2-5/6)=7/2

=>-1/3x=7/2

hay x=-21/2

c: (4-x)(3x+5)=0

=>4-x=0 hoặc 3x+5=0

=>x=4 hoặc x=-5/3

d: x/16=50/32

=>x/16=25/16

hay x=25

e: =>2x-3=-1/4-3/2=-1/4-6/4=-7/4

=>2x=-7/4+3=5/4

hay x=5/8

Bài 6: Tìm x, biết a) $\dfrac{3}{2}$ x $\dfrac{4}{5}$ - X =$\dfrac{2}{3}$ b) X x 3$\dfrac{1}{3}$ = 3$\dfrac{1}{3}$ : 4$\dfrac{1}{4}$ c) 5$\dfrac{2}{3}$ : x = 3$\dfrac{2}{3}$ -...

MP

Minh Phương Trần

13 tháng 7 2023

#Toán lớp 5

2

KT

『Kuroba ム Tsuki Ryoo ︵²ᵏ⁷』

13 tháng 7 2023

`@` `\text {Ans}`

`\downarrow`

`a)`

$\dfrac{3}{2}\times\dfrac{4}{5}-x=\dfrac{2}{3}$

$\dfrac{6}{5}-x=\dfrac{2}{3}$

$x=\dfrac{6}{5}-\dfrac{2}{3}$

$x=\dfrac{18}{15}-\dfrac{10}{15}$

$x=\dfrac{8}{15}$

Vậy, `x =`$\dfrac{8}{15}$

`b)`

$x\times3\dfrac{1}{3}=3\dfrac{1}{3}\div4\dfrac{1}{4}$

$x\times\dfrac{10}{3}=\dfrac{40}{51}$

$x=\dfrac{40}{51}\div\dfrac{10}{3}$

$x=\dfrac{4}{17}$

Vậy, $x=\dfrac{4}{17}$

`c)`

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

$\dfrac{17}{3}\div x=\dfrac{7}{6}$

$x=\dfrac{17}{3}\div\dfrac{7}{6}$

$x=\dfrac{34}{7}$

Vậy, `x = `$\dfrac{34}{7}$

ND

Nguyễn Đức Trí

VIP

13 tháng 7 2023

a) $\dfrac{3}{2}x\dfrac{4}{5}-x=\dfrac{2}{3}\Rightarrow\dfrac{6}{5}-x=\dfrac{2}{3}\Rightarrow x=\dfrac{6}{5}-\dfrac{2}{3}=\dfrac{18}{15}-\dfrac{10}{15}=\dfrac{8}{15}$

b) $x.3\dfrac{1}{3}=3\dfrac{1}{3}:4\dfrac{1}{4}\Rightarrow\dfrac{10}{3}.x=\dfrac{10}{3}:\dfrac{17}{4}\Rightarrow\dfrac{10}{3}.x=\dfrac{10}{3}.\dfrac{4}{17}\Rightarrow x=\dfrac{10}{3}.\dfrac{4}{17}:\dfrac{10}{3}=\dfrac{10}{3}.\dfrac{4}{17}.\dfrac{3}{10}=\dfrac{4}{17}$

c) $5\dfrac{2}{3}:x=3\dfrac{2}{3}-2\dfrac{1}{2}\Rightarrow\dfrac{17}{3}:x=\dfrac{11}{3}-\dfrac{5}{2}\Rightarrow\dfrac{17}{3}:x=\dfrac{22}{6}-\dfrac{15}{6}\Rightarrow\dfrac{17}{3}:x=\dfrac{7}{6}\Rightarrow x=\dfrac{17}{3}:\dfrac{7}{6}=\dfrac{17}{3}.\dfrac{7}{6}=\dfrac{119}{18}$

KJ

❖ Khang/GD❄ 『ʈєɑɱ❖Hoàng๖ۣۜGia☆』

29 tháng 1 2022

Tìm x...

2

KS

Kudo Shinichi AKIRA^_^

29 tháng 1 2022

Chia nhỏ ra

NL

Nguyễn Lê Phước Thịnh

29 tháng 1 2022

a: =>1/2x=7/2-2/3=21/6-4/6=17/6

=>x=17/3

b: =>2/3:x=-7-1/3=-22/3

=>x=2/3:(-22/3)=-1/11

c: =>1/3x+2/5x-2/5=0

=>11/15x=2/5

hay x=6/11

d: =>2x-3=0 hoặc 6-2x=0

=>x=3/2 hoặc x=3

KJ

❖ Khang/GD❄ 『ʈєɑɱ❖Hoàng๖ۣۜGia☆』

12 tháng 3 2022

Tìm x...

1

NT

nguyen thi chuyen

12 tháng 3 2022

a)4/5+x=2/3

x=2/3-4/5

x=-2/15

b)-5/6-x=2/3

x=-5/6-2/3

x=-3/2

c)1/2x+3/4=-3/10

1/2x=-3/10-3/4

1/2x=-21/20

x=-21/20:1/2

x=-21/10

d)x/3-1/2=1/5

x/3=1/5+1/2

x/3=7/10

10x/30=21/30

10x=21

x=21:10

x=21/10

NL

Nguyễn Linh

3 tháng 2 2022

Giải các phương trình...

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...

#Toán lớp 8

1

NL

Nguyễn Lê Phước Thịnh

3 tháng 2 2022

a: =>10x-4=15-9x

=>19x=19

hay x=1

b: $\Leftrightarrow3\left(10x+3\right)=36+4\left(8x+6\right)$

=>30x+9=36+32x+24

=>30x-32x=60-9

=>-2x=51

hay x=-51/2

c: $\Leftrightarrow2x+\dfrac{6}{5}=5-\dfrac{13}{5}-x$

=>3x=6/5

hay x=2/5

d: $\Leftrightarrow\dfrac{7x}{8}-\dfrac{5\left(x-9\right)}{1}=\dfrac{20x+1.5}{6}$

$\Leftrightarrow21x-120\left(x-9\right)=4\left(20x+1.5\right)$

=>21x-120x+1080=80x+60

=>-179x=-1020

hay x=1020/179

e: $\Leftrightarrow5\left(7x-1\right)+60x=6\left(16-x\right)$

=>35x-5+60x=96-6x

=>95x+6x=96+5

=>x=1

f: $\Leftrightarrow6\left(x+4\right)+30\left(-x+4\right)=10x-15\left(x-2\right)$

=>6x+24-30x+120=10x-15x+30

=>-24x+96=-5x+30

=>-19x=-66

hay x=66/19

Đúng(3)

HT

Ha Thù

11 tháng 9 2023

#Toán lớp 7

3

VN

Võ Ngọc Phương

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

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

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

$#Wendy.Dang$

Đúng(2)

HT

Ha Thù

11 tháng 9 2023

Uh, chừa sau k dám học muộn nx

TD

Thầy Đức Anh

Giáo viên VIP

27 tháng 4 2022

Tìm $x$, biết :
a) $\left(\dfrac{1}{2}+1,5\right) \cdot x=\dfrac{1}{5}$
b) $\left(-1 \dfrac{3}{5}+x\right): \dfrac{12}{13}=2 \dfrac{1}{6}$
c) $\left(x: 2 \dfrac{1}{3}\right) \cdot \dfrac{1}{7}=\dfrac{-3}{8}$
d) $\dfrac{-4}{7} \cdot x+\dfrac{7}{5}=\dfrac{1}{8}:\left(-1 \dfrac{2}{3}\right)$

#Toán lớp 7

13

YN

Yen Nhi

21 tháng 6 2022

$a)\left(\dfrac{1}{2}+1,5\right)x=\dfrac{1}{5}$

$\Rightarrow2x=\dfrac{1}{5}$

$\Rightarrow x=\dfrac{1}{10}$

$b)\left(-1\dfrac{3}{5}+x\right):\dfrac{12}{13}=2\dfrac{1}{6}$

$\Leftrightarrow-\dfrac{8}{5}+x=\dfrac{13}{6}.\dfrac{12}{13}$

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

$\Leftrightarrow x=\dfrac{18}{5}$

$c)\left(x:2\dfrac{1}{3}\right).\dfrac{1}{7}=-\dfrac{3}{8}$

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

$\Leftrightarrow x=-\dfrac{21}{8}.\dfrac{7}{3}$

$\Leftrightarrow x=-\dfrac{49}{8}$

$d)-\dfrac{4}{7}x+\dfrac{7}{5}=\dfrac{1}{8}:\left(-1\dfrac{2}{3}\right)$

$\Leftrightarrow-\dfrac{4}{7}x+\dfrac{7}{5}=-\dfrac{3}{40}$

$\Leftrightarrow-\dfrac{4}{7}x=-\dfrac{59}{40}$

$\Leftrightarrow x=\dfrac{413}{160}$

T

TINH

13 tháng 7 2022

a) $\left(\dfrac{1}{2}+1,5\right) \cdot x=\dfrac{1}{5}$

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

$x=\dfrac{1}{5}: 2$

$x=\dfrac{1}{10}$
b) $\left(-1 \dfrac{3}{5}+x\right): \dfrac{12}{13}=2 \dfrac{1}{6}$

$\dfrac{3}{5}+x=\dfrac{13}{6} \cdot \dfrac{12}{13}$
$\dfrac{3}{5}$

$\dfrac{3}{5}$
c) $\left(x: 2 \dfrac{1}{3}\right) \cdot \dfrac{1}{7}=\dfrac{-3}{8}$

$\cdot \dfrac{3}{7} \cdot \dfrac{1}{7}=\dfrac{-3}{8}$

$x=\dfrac{-3}{8}: \dfrac{3}{49}$
$x=\dfrac{-49}{8}=-6 \dfrac{1}{8}$
d) $\dfrac{-4}{7} \cdot x+\dfrac{7}{5}=\dfrac{1}{8}:\left(-1 \dfrac{2}{3}\right)$

$\dfrac{-4}{7} x+\dfrac{7}{5}=\dfrac{1}{8} \cdot \dfrac{-3}{5}$
$-\dfrac{4}{7} x=\dfrac{-3}{40}-\dfrac{7}{5} \\ x=\dfrac{-59}{40}: \dfrac{-4}{7}=\dfrac{413}{160}=2 \dfrac{93}{160}$