$\dfrac{x-3}{13} \dfrac{x-3}{14}=\dfrac{x-3}{15} \dfrac{x-3}{16}$Tìm x

2

H

⭐Hannie⭐

3 tháng 3 2023

`(x-3)/13+(x-3)/14=(x-3)/15+(x-3)/16`

`=>(x-3).(1/13+1/14-1/15-1/16)=0`

`=>x-3=0`

`=>x=3`

H9

HT.Phong (9A5)

CTVHS

3 tháng 3 2023

$\dfrac{x-3}{13}+\dfrac{x-3}{14}=\dfrac{x-3}{15}+\dfrac{x-3}{16}$

$\Leftrightarrow\dfrac{x-3}{13}+\dfrac{x-3}{14}-\dfrac{x-3}{15}-\dfrac{x-3}{16}=0$

$\Leftrightarrow\left(x-3\right).\left(\dfrac{1}{13}+\dfrac{1}{14}-\dfrac{1}{15}-\dfrac{1}{16}\right)=0$

$\Leftrightarrow x-3=0$( Vì $\dfrac{1}{13}+\dfrac{1}{14}-\dfrac{1}{15}-\dfrac{1}{16}>0$)

$\Leftrightarrow x-3=0\Rightarrow x=3$

LH

Lê Hoàng Khánh

10 tháng 8 2021

Tìm x, biết.

$\dfrac{x-3}{13}+\dfrac{x-3}{14}=\dfrac{x-3}{15}+\dfrac{x-3}{16}$

#Toán lớp 7

2

HN

hà nguyễn

10 tháng 8 2021

$\dfrac{x-3}{13}+\dfrac{x-3}{14}=\dfrac{x-3}{15}+\dfrac{x-3}{16}$

$\Leftrightarrow\dfrac{1680.\left(x-3\right)+1560.\left(x-3\right)-1456.\left(x-3\right)-1365.\left(x-3\right)}{21840}=0$

$\Leftrightarrow\left(x-3\right).\left(1680+1560-1456-1365\right)=0$

$\Leftrightarrow\left(x-3\right).419=0$

$\Leftrightarrow419x=1257$

$\Leftrightarrow x=3$

AH

Akai Haruma

Giáo viên

10 tháng 8 2021

Lời giải:

$\frac{x-3}{13}+\frac{x-3}{14}=\frac{x-3}{15}+\frac{x-3}{16}$

$(x-3)\left(\frac{1}{13}+\frac{1}{14}\right)=(x-3)\left(\frac{1}{15}+\frac{1}{16}\right)$

$(x-3)\left[\left(\frac{1}{13}+\frac{1}{14}\right)-\left(\frac{1}{15}+\frac{1}{16}\right)\right]=0$

Ta thấy:

$\frac{1}{13}>\frac{1}{15}; \frac{1}{14}>\frac{1}{16}\Rightarrow \frac{1}{13}+\frac{1}{14}> \frac{1}{15}+\frac{1}{16}$

Do đó biểu thức trong ngoặc vuông lớn hơn $0$ hay khác $0$

$\Rightarrow x-3=0$

$\Leftrightarrow x=3$

a)$\dfrac{2}{3}$x-1=$\dfrac{3}{2}$b)| 5x - $\dfrac{1}{2}$| - $\dfrac{2}{7}$=...

TT

Trần Thị Minh Ngọc

16 tháng 7 2021

Đọc tiếp

3

NL

Nguyễn Lê Phước Thịnh

17 tháng 7 2021

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

$\Leftrightarrow x\cdot\dfrac{2}{3}=\dfrac{5}{2}$

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

b) Ta có: $\left|5x-\dfrac{1}{2}\right|-\dfrac{2}{7}=25\%$

$\Leftrightarrow\left|5x-\dfrac{1}{2}\right|=\dfrac{1}{4}+\dfrac{2}{7}=\dfrac{15}{28}$

$\Leftrightarrow\left[{}\begin{matrix}5x-\dfrac{1}{2}=\dfrac{15}{28}\\5x-\dfrac{1}{2}=\dfrac{-15}{28}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}5x=\dfrac{29}{28}\\5x=\dfrac{-1}{28}\end{matrix}\right.$

$\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{29}{140}\\x=\dfrac{-1}{140}\end{matrix}\right.$

NL

Nguyễn Lê Phước Thịnh

17 tháng 7 2021

c) Ta có: $\dfrac{x-3}{4}=\dfrac{16}{x-3}$

$\Leftrightarrow\left(x-3\right)^2=64$

$\Leftrightarrow\left[{}\begin{matrix}x-3=8\\x-3=-8\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=11\\x=-5\end{matrix}\right.$

d) Ta có: $\dfrac{-8}{13}+\dfrac{7}{17}+\dfrac{21}{31}\le x\le\dfrac{-9}{14}+4-\dfrac{5}{14}$

$\Leftrightarrow\dfrac{3246}{6851}\le x\le3$

$\Leftrightarrow x\in\left\{1;2;3\right\}$

9 - 3 x ( X - 9 ) = 64 + 6 x ( X + 1 ) 70$\dfrac{X}{13}+\dfrac{15}{26}=\dfrac{46}{52}$$\dfrac{11}{14}-\dfrac{3}{X}=\dfrac{5}{14}$5 x ( 3 + 7 x X ) = 40X x 6 + 12 : 3 = 120X x 3,7 + X x 6,3 = 120( 15 x 24 - X ) : 0,25 = 100 : $\dfrac{1}{4}$71 + 65 x 4 = $\dfrac{X+140}{X}$+ 260( X +1 ) + ( X + 4 ) + ( x + 7 ) + ...... + (X + 28 ) = 155đây là bài tìm...

NQ

Nguyễn Quang Vũ Anh

14 tháng 6 2021

Đọc tiếp

#Toán lớp 5

1

T

꧁_͏ͥ͏_͏ͣ͏_͏ͫ͏ ¡亗ᵛᶰシ๖ۣۜT๖ۣۜR๖ۣۜÂ๖ۣ...

14 tháng 6 2021

Giải:

$9-3\times\left(x-9\right)=6$

$3\times\left(x-9\right)=9-6$

$3\times\left(x-9\right)=3$

$x-9=3:3$

$x-9=1$

$x=1+9$

$x=10$

$4+6\times\left(x+1\right)=70$

$6\times\left(x+1\right)=70-4$

$6\times\left(x+1\right)=66$

$x+1=66:6$

$x+1=11$

$x=11-1$

$x=10$

$\dfrac{x}{13}+\dfrac{15}{26}=\dfrac{46}{52}$

$\dfrac{x}{13}=\dfrac{23}{26}-\dfrac{15}{26}$

$\dfrac{x}{13}=\dfrac{4}{13}$

$\Rightarrow x=4$

$\dfrac{11}{14}-\dfrac{3}{x}=\dfrac{5}{14}$

$\dfrac{3}{x}=\dfrac{11}{14}-\dfrac{5}{14}$

$\dfrac{3}{x}=\dfrac{3}{7}$

$\Rightarrow x=7$

$5\times\left(3+7\times x\right)=40$

$3+7\times x=40:5$

$3+7\times x=8$

$7\times x=8-3$

$7\times x=5$

$x=5:7$

$x=\dfrac{5}{7}$

$x\times6+12:3=120$

$x\times6+4=120$

$x\times6=120-4$

$x\times6=116$

$x=116:6$

$x=\dfrac{58}{3}$

$x\times3,7+x\times6,3=120$

$x\times\left(3,7+6,3\right)=120$

$x\times10=120$

$x=120:10$

$x=12$

$\left(15\times24-x\right):0,25=100:\dfrac{1}{4}$

$\left(360-x\right):0,25=400$

$360-x=400.0,25$

$360-x=100$

$x=360-100$

$x=260$

$71+65\times4=\dfrac{x+140}{x}+260$

$\left(x+140\right):x+260=71+260$

$x:x+140:x+260=331$

$1+140:x+260=331$

$140:x=331-1-260$

$140:x=70$

$x=140:70$

$x=2$

$\left(x+1\right)+\left(x+4\right)+\left(x+7\right)+...+\left(x+28\right)=155$

$10\times x+\left(1+4+7+...+28\right)=155$

Số số hạng $\left(1+4+7+...+28\right)$ :

$\left(28-1\right):3+1=10$

Tổng dãy $\left(1+4+7+...+28\right)$ :

$\left(1+28\right).10:2=145$

$\Rightarrow10\times x+145=155$

$10\times x=155-145$

$10\times x=10$

$x=10:10$

$x=1$

Đều theo cách lớp 5 nha em!

NT

Nguyễn Thị Minh Thu

24 tháng 9 2023

$\dfrac{7}{13}$ : $x$ = $\dfrac{14}{39}$

$x$ x $\dfrac{3}{5}$ = $\dfrac{14}{15}$

#Toán lớp 5

3

KT

『Kuroba ム Tsuki Ryoo ︵²ᵏ⁷』

24 tháng 9 2023

`#3107`

`7/13 \div x = 14/39`

`=> x = 7/13 \div 14/39`

`=> x = 3/2`

Vậy, `x = 3/2`

________

`x \times 3/5 = 14/15`

`=> x = 14/15 \div 3/5`

`=> x = 14/9`

Vậy, `x=14/9.`

H9

HT.Phong (9A5)

CTVHS

24 tháng 9 2023

$\dfrac{7}{13}:x=\dfrac{14}{39}$

$x=\dfrac{7}{13}:\dfrac{14}{39}$

$x=\dfrac{7}{13}\times\dfrac{39}{14}$

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

___

$x\times\dfrac{3}{5}=\dfrac{14}{15}$

$x=\dfrac{14}{15}:\dfrac{3}{5}$

$x=\dfrac{14}{15}\times\dfrac{5}{3}$

$x=\dfrac{14}{9}$

VT

vũ thu hằng

9 tháng 1 2022

$\dfrac{x+1}{15}$+$\dfrac{x+2}{14}$=$\dfrac{x+3}{13}$+$\dfrac{x+4}{12}$

1

KS

Kudo Shinichi

9 tháng 1 2022

$\dfrac{x+1}{15}+\dfrac{x+2}{14}=\dfrac{x+3}{13}+\dfrac{x+4}{12}\\ \Rightarrow\left(\dfrac{x+1}{15}+1\right)+\left(\dfrac{x+2}{14}+1\right)-\left(\dfrac{x+3}{13}+1\right)-\left(\dfrac{x+4}{12}+1\right)=0\\ \dfrac{x+16}{15}+\dfrac{x+16}{14}-\dfrac{x+16}{13}-\dfrac{x+16}{12}=0\\ \left(x+16\right)\left(\dfrac{1}{15}+\dfrac{1}{14}-\dfrac{1}{13}-\dfrac{1}{12}\right)=0\\ x+16=0\\ x=-16$

Đúng(4)

CN

Chi Nghiêm

20 tháng 9 2023

$a,\dfrac{15-x}{14}=\dfrac{5}{7}$

$b,\dfrac{x}{9}=\dfrac{17}{3}$

$c,15-\dfrac{x}{2}=\dfrac{3}{7}$

Tìm x

#Toán lớp 5

2

H

⭐Hannie⭐

20 tháng 9 2023

$\dfrac{15-x}{14}=\dfrac{5}{7}\\ \left(15-x\right)\times7=5\times14\\ \left(15-x\right)\times7=70\\ 15-x=70:7\\ 15-x=10\\ x=15-10\\ x=5$

__

$\dfrac{x}{9}=\dfrac{17}{3}\\ x\times3=17\times9\\ x\times3=153\\ x=153:3\\ x=51$

__

$15-\dfrac{x}{2}=\dfrac{3}{7}\\ \dfrac{x}{2}=15-\dfrac{3}{7}\\ \dfrac{x}{2}=\dfrac{102}{7}\\ x\times7=102\times2\\ x\times7=204\\ x=204:7\\ x=\dfrac{204}{7}$

CN

Chi Nghiêm

20 tháng 9 2023

???

NL

Nguyễn Lê Hồng Thái

17 tháng 4 2021

a, $\dfrac{x-2}{15}+\dfrac{x-3}{14}+\dfrac{x-4}{13}+\dfrac{x-5}{12}=4$

b, $\dfrac{x+1}{19}+\dfrac{x+2}{18}+\dfrac{x+3}{17}+...+\dfrac{x+18}{2}+18=0$

Cảm ơn khi đã giúp mình

2

NL

Nguyễn Lê Phước Thịnh

17 tháng 4 2021

a) Ta có: $\dfrac{x-2}{15}+\dfrac{x-3}{14}+\dfrac{x-4}{13}+\dfrac{x-5}{12}=4$

$\Leftrightarrow\dfrac{x-2}{15}-1+\dfrac{x-3}{14}-1+\dfrac{x-4}{13}-1+\dfrac{x-5}{12}-1=0$

$\Leftrightarrow\dfrac{x-17}{15}+\dfrac{x-17}{14}+\dfrac{x-17}{13}+\dfrac{x-17}{12}=0$

$\Leftrightarrow\left(x-17\right)\left(\dfrac{1}{15}+\dfrac{1}{14}+\dfrac{1}{13}+\dfrac{1}{12}\right)=0$

mà $\dfrac{1}{15}+\dfrac{1}{14}+\dfrac{1}{13}+\dfrac{1}{12}>0$

nên x-17=0

hay x=17

Vậy: x=17

NL

Nguyễn Lê Phước Thịnh

17 tháng 4 2021

b) Ta có: $\dfrac{x+1}{19}+\dfrac{x+2}{18}+\dfrac{x+3}{17}+...+\dfrac{x+18}{2}+18=0$

$\Leftrightarrow\dfrac{x+1}{19}+1+\dfrac{x+2}{18}+1+\dfrac{x+3}{17}+1+...+\dfrac{x+18}{2}+1=0$

$\Leftrightarrow\dfrac{x+20}{19}+\dfrac{x+20}{18}+\dfrac{x+20}{17}+...+\dfrac{x+20}{2}=0$

$\Leftrightarrow\left(x+20\right)\left(\dfrac{1}{19}+\dfrac{1}{18}+\dfrac{1}{17}+...+\dfrac{1}{2}\right)=0$

mà $\dfrac{1}{19}+\dfrac{1}{18}+\dfrac{1}{17}+...+\dfrac{1}{2}>0$

nên x+20=0

hay x=-20

Vậy: x=-20

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

HK

Hoàng Kim Nhung

13 tháng 7 2023

tìm số tự nhin x bt

a.$x-$$\dfrac{5}{14}=\dfrac{3}{7}-\dfrac{1}{14}$ b.$\dfrac{2}{9}:x=\dfrac{1}{2}+\dfrac{2}{3}$ c.$\dfrac{6}{32:x}=\dfrac{12}{16}$

#Toán lớp 4

5

NL

Nguyễn Lê Phước Thịnh

13 tháng 7 2023

a: =>x-5/14=6/14-1/14=5/14

=>x=10/14=5/7

b; =>2/9:x=3/6+4/6=7/6

=>x=2/9:7/6=2/9*6/7=4/21

c: =>32:x=8

=>x=4

NN

Ng Ngọc

13 tháng 7 2023

`@` `\text {Answer}`

`\downarrow`

`a,`

`x - 5/14 = 3/7 - 1/14`

`x - 5/14 = 5/14`

`=> x = 5/14 + 5/14`

`=> x = 5/7`

Vậy, `x = 5/7`

`b,`

`2/9 \div x = 1/2 + 2/3`

`2/9 \div x = 7/6`

`x = 2/9 \div 7/6`

`x = 4/21`

Vậy, `x = 4/21`

`c,`

$\dfrac{6}{32\div x}=\dfrac{12}{16}$

`6/(32 \div x) = 3/4`

`32 \div x = 6 \div 3/4`

`32 \div x = 8`

` x = 32 \div 8`

`x = 4`

Vậy, `x = 4`