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MN
20 tháng 2 2021
\(3\left(x-2\right)+4\left(x-5\right)=23\)
\(\Rightarrow3x-6+4x-20-23=0\)
\(\Rightarrow7x-49=0\)
\(\Rightarrow x=7\)
20 tháng 2 2021
3(x-2)+4(x-5)=23
<=>3x-6+4x-20=23
<=>7x-26=23
<=>7x=49
<=>x=7
Vậy x=7
NL
2
X
7 tháng 7 2015
1. 4(x+41)=400
<=>x+41=100
<=>x=59
2.11(x-9)=77
<=>x-9=7
<=>x=16
3.5(x-9)=350
<=>x-9=70
<=>x=79
4.2x-49=3.32
<=>2x=3.32+49
<=>2x=76
<=>x=38
5.200-(2x+6)=43
<=>200-2x-6=64
<=>-2x=64-200+6
<=>-2x=-130
<=>x=65
7 tháng 7 2015
1) 4(x+41)=400
x+41=400:4
x+41=100
x=100-41
x=59
2) 11(x-9)=77
x-9=77:11
x-9=7
x=7+9
x=16
3) 5(x-9)=350
x-9=350:5
x-9=70
x=70+9
x=79
4) 2x-49=3.3\(^2\)
2x-49=3\(^3\)
2x-49=27
2x=27+49
2x=76
x=76:2
x=38
5, 200-(2x+6)=4\(^3\)
200-(2x+6)=64
2x+6=200-64
2x+6=136
2x=136-6
2x=130
x=130:2
x=65
đúng nha
thanks bn nhìu
29 tháng 1 2023
a: =>x/15=-3/5
=>x=-9
b: =>36/y=4/7
=>y=36:4/7=63
c: =>xy=-12
=>(x,y) thuộc {(-1;12); (12;-1); (1;-12); (-12;1); (2;-6); (-6;2); (6;-2); (-2;6); (3;-4); (-4;3); (-3;4); (4;-3)}
d: =>xy=-18
=>(x,y) thuộc {(1;-18); (-18;1); (-1;18);(18;-1); (2;-9); (-9;2); (-2;9); (9;-2); (3;-6); (-6;3); (-3;6); (6;-3)}
KK
19 tháng 3 2019
1a) \(\frac{x-3}{x+7}=\frac{-5}{-6}\)
=> \(\frac{x-3}{x+7}=\frac{5}{6}\)
=> (x - 3).6 = 5.(x + 7)
=> 6x - 18 = 5x + 35
=> 6x - 5x = 35 + 18
=> x = 53
b) \(\frac{x-7}{x+3}=\frac{4}{3}\)
=> (x - 7). 3 = (x + 3). 4
=> 3x - 21 = 4x + 12
=> 3x - 4x = 12 + 21
=> -x = 33
=> x = -33
c) \(\frac{x-10}{6}=-\frac{5}{18}\)
=> (x - 10) . 18 = -5 . 6
=> 18x - 180 = -30
=> 18x = -30 + 180
=> 18x = 150
=> x = 150 : 18 = 25/3
KK
19 tháng 3 2019
d) \(\frac{x-2}{4}=\frac{25}{x-2}\)
=> (x - 2)(x - 2) = 25 . 4
=> (x - 2)2 = 100
=> (x - 2)2 = 102
=> \(\orbr{\begin{cases}x-2=10\\x-2=-10\end{cases}}\)
=> \(\orbr{\begin{cases}x=12\\x=-8\end{cases}}\)
e) \(\frac{7}{x}=\frac{x}{28}\)
=> 7 . 28 = x . x
=> 196 = x2
=> x2 = 142
=> \(\orbr{\begin{cases}x=14\\x=-14\end{cases}}\)
f) \(\frac{40+x}{77-x}=\frac{6}{7}\)
=> (40 + x) . 7 = (77 - x).6
=> 280 + 7x = 462 - 6x
=> 280 - 462 = -6x + 7x
=> -182 = x
=> x = -182
18 tháng 4 2023
\(1,-\dfrac{4}{7}+\dfrac{2}{3}\times\dfrac{-9}{14}\)
\(=\dfrac{-4}{7}+\dfrac{-18}{42}\)
\(=\dfrac{-4\times6}{7\times6}+\dfrac{-18}{42}\)
\(=\dfrac{-20}{42}+\dfrac{-18}{42}\)
\(=-\dfrac{38}{42}\)
\(=-\dfrac{19}{21}\)
\(2,\dfrac{17}{13}-\left(\dfrac{4}{13}-11\right)\)
\(=\dfrac{17}{13}-\dfrac{4}{13}+11\)
\(=\dfrac{13}{13}+11\)
\(=1+11\)
\(=12\)
\(3,8\dfrac{2}{7}-\left(3\dfrac{4}{9}+4\dfrac{2}{7}\right)\)
\(=\dfrac{58}{7}-\left(\dfrac{31}{9}+\dfrac{30}{7}\right)\)
\(=\dfrac{58}{7}-\dfrac{31}{9}-\dfrac{30}{7}\)
\(=\dfrac{58}{7}-\dfrac{30}{7}-\dfrac{31}{9}\)
\(=\dfrac{28}{7}-\dfrac{31}{9}\)
\(=\dfrac{28\times9}{7\times9}-\dfrac{31\times7}{9\times7}\)
\(=\dfrac{252}{63}-\dfrac{217}{63}\)
\(=\dfrac{35}{63}\)
\(=\dfrac{5}{9}\)
\(5,\left(\dfrac{2}{3}-1\dfrac{1}{2}\right):\dfrac{4}{3}+\dfrac{1}{2}\)
\(=\left(\dfrac{2}{3}-\dfrac{3}{2}\right):\dfrac{4}{3}+\dfrac{1}{2}\)
\(=\left(\dfrac{2\times2}{3\times2}-\dfrac{3\times3}{2\times3}\right):\dfrac{4}{3}+\dfrac{1}{2}\)
\(=\left(\dfrac{4}{6}-\dfrac{9}{6}\right):\dfrac{4}{3}+\dfrac{1}{2}\)
\(=\dfrac{-5}{6}:\dfrac{4}{3}+\dfrac{1}{2}\)
\(=\dfrac{-5}{6}\times\dfrac{3}{4}+\dfrac{1}{2}\)
\(=\dfrac{-15}{24}+\dfrac{1}{2}\)
\(=\dfrac{-15}{24}+\dfrac{1\times12}{2\times12}\)
\(=\dfrac{-15}{24}+\dfrac{12}{24}\)
\(=\dfrac{-3}{24}\)
\(=-\dfrac{1}{8}\)
\(6,\dfrac{-5}{13}+\dfrac{2}{5}+\dfrac{-8}{13}+\dfrac{3}{5}-\dfrac{3}{7}\)
\(=\left(\dfrac{-5}{13}+\dfrac{-8}{13}\right)+\left(\dfrac{2}{5}+\dfrac{3}{5}\right)-\dfrac{3}{7}\)
\(=\dfrac{-13}{13}+\dfrac{5}{5}-\dfrac{3}{7}\)
\(=-1+1-\dfrac{3}{7}\)
\(=-\dfrac{3}{7}\)
\(7,\dfrac{6}{5}\times\dfrac{3}{7}+\dfrac{6}{5}:\dfrac{7}{10}+\dfrac{6}{5}\)
\(=\dfrac{6}{5}\times\dfrac{3}{7}+\dfrac{6}{5}\times\dfrac{10}{7}+\dfrac{6}{5}\)
\(=\dfrac{6}{5}\times\left(\dfrac{3}{7}+\dfrac{10}{7}+1\right)\)
\(=\dfrac{6}{5}\times\left(\dfrac{3}{7}+\dfrac{10}{7}+\dfrac{1\times7}{1\times7}\right)\)
\(=\dfrac{6}{5}\times\left(\dfrac{3}{7}+\dfrac{10}{7}+\dfrac{7}{7}\right)\)
\(=\dfrac{6}{5}\times\dfrac{20}{7}\)
\(=\dfrac{120}{35}\)
\(=\dfrac{24}{7}\)
CN
5 tháng 1 2018
a) 71 - (33 + x) = 26
⇔ 71 - 33 - x = 26
⇔ 38 - x = 26
⇔ x = 38 - 26
⇔ x = 12
b) (x + 73) - 26 = 76
⇔ x + 73 - 26 = 76
⇔ x + 47 = 76
⇔ x = 76 - 47
⇔ x = 29
c) 45 - (x + 9) = 6
⇔ 45 - x - 9 = 6
⇔ 36 - x = 6
⇔ x = 36 - 6
⇔ x = 30
d) 89 - (73 - x) = 20
⇔ 89 - 73 + x = 20
⇔ 16 + x = 20
⇔ x = 20 - 16
⇔ x = 4
e) (x + 7) - 25 = 13
⇔ x + 7 - 25 = 13
⇔ x - 18 = 13
⇔ x = 13 + 18
⇔ x = 31
f) 198 - (x + 4) = 120
⇔ 198 - x - 4 = 120
⇔ 194 - x = 120
⇔ x = 194 - 120
⇔ x = 74
g) 140 : (x - 8) = 7
⇔ x - 8 = 140 : 7
⇔ x - 8 = 20
⇔ x = 20 + 8
⇔ x = 28
h) 4(x + 41) = 400
⇔ x + 41 = 400 : 4
⇔ x + 41 = 100
⇔ x = 100 - 41
⇔ x = 59
i) 11(x - 9) = 77
⇔ x - 9 = 77 : 11
⇔ x - 9 = 7
⇔ x = 7 + 9
⇔ x = 16
j) 5(x - 9) = 350
⇔ x - 9 = 350 : 5
⇔ x - 9 = 70
⇔ x = 70 + 9
⇔ x = 79
k) 2x - 49 = 5.32
⇔ 2x - 49 = 45
⇔ 2x = 45 + 49
⇔ 2x = 94
⇔ x = 94 : 2
⇔ x = 47
l) 200 - (2x + 6) = 43
⇔ 200 - 2x - 6 = 64
⇔ 194 - 2x = 64
⇔ 2x = 194 - 64
⇔ 2x = 130
⇔ x = 130 : 2
⇔ x = 65
TT
5 tháng 1 2018
a) 71 - (33 + x) = 26
⇔ 33+x=71-26
⇔ 33 + x = 45
⇔ x = 45 - 33
⇔ x = 12
Vậy x=12
b) (x + 73) - 26 = 76
⇔ (x + 73) = 76+26
⇔ x + 73 = 102
⇔ x = 102-73
⇔ x = 29
Vậy x=29
c) 45 - (x + 9) = 6
⇔ x + 9 = 45 - 6
⇔ x+9 = 39
⇔ x = 39 - 9
⇔ x = 30
Vậy x=30
19 tháng 3 2020
nhiều quá :((
\(a,2\left(x-5\right)-3\left(x+7\right)=14\)
\(2x-10-3x-21=14\)
\(-x-31=14\)
\(-x=45\)
\(x=45\)
\(b,5\left(x-6\right)-2\left(x+3\right)=12\)
\(5x-30-2x-6=12\)
\(3x-36==12\)
\(3x=48\)
\(x=16\)
\(c,3\left(x-4\right)-\left(8-x\right)=12\)
\(3x-12-8+x=0\)
\(4x-20=0\)
\(4x=20\)
\(x=5\)
Cố nốt nha bn !
LM
19 tháng 3 2020
cảm ơn, bn nha:)))
mà hình như bạn TOP 3 trả lời câu hỏi pải ko nhỉ???
3/4x = -6/7
=> x = -6/7 : 3/4
=> x = -8/7
7/9 - 2/3x = -5/6
=> 2/3x = 7/9 - ( - 5/6 )
=> 2/3x = 19/18
=> x = 19/18 : 2/3
=> x = 19/12