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3 tháng 7 2017

\(x⋮12;25;30\Rightarrow x\in BC\left(12;25;30\right)\)

\(12=2^2.3;25=5^2;30=2.3.5\)

\(BCNN\left(12;25;30\right)=2^2.3.5^2=300\)

\(BC\left(12;25;30\right)=B\left(300\right)\)

\(B\left(300\right)=\left\{0;300;600;....\right\}\)

\(0\le x\le500\Rightarrow x=300\)

\(\left(3x-2^4\right).7^3=2.7^4\)

\(\left(3x-16\right)=2.7\)

\(3x-16=14\)

\(3x=30\)

\(x=10\)

\(\left|x-5\right|=16+2.\left(-3\right)\)

\(\left|x-5\right|=10\)

\(\Leftrightarrow x-5=10\Rightarrow x=15\)

\(\Leftrightarrow x-5=-10\Rightarrow x=-5\)

21 tháng 8 2017

a, -5/7+ 1+ 30/-7< x < -1/6+ 1/3 +5/6
<=> -4< x <1
<=> x = -3; -2; -1; 0

22 tháng 8 2017

a, \(\dfrac{-5}{7}+1+\dfrac{30}{-7}\le x\le\dfrac{-1}{6}+\dfrac{1}{3}+\dfrac{5}{6}\)
<=> -4 \(\le x\le1\)
Do x \(\in Z\Rightarrow x=-4;-3;-2;-1;0;1\)
b, \(\dfrac{1}{2}-\left(\dfrac{1}{3}+\dfrac{1}{4}\right)< x< \dfrac{1}{48}-\left(\dfrac{1}{16}-\dfrac{1}{6}\right)\)
<=> -\(\dfrac{1}{12}< x< \dfrac{1}{8}\)
Do x \(\in Z\Rightarrow x=0;1\)
@Mai Tran

a: \(\dfrac{2}{3}x-\dfrac{1}{2}=\dfrac{1}{10}\)

nên \(\dfrac{2}{3}x=\dfrac{1}{10}+\dfrac{1}{2}=\dfrac{6}{10}=\dfrac{3}{5}\)

hay \(x=\dfrac{3}{5}:\dfrac{2}{3}=\dfrac{9}{10}\)

b: \(\Leftrightarrow5-\dfrac{4}{7}x=13\)

nên 4/7x=-8

hay x=-12

c: \(\left(x+\dfrac{1}{2}\right)\cdot\left(\dfrac{2}{3}-2x\right)=0\)

=>x+1/2=0 hoặc 2/3-2x=0

=>x=-1/2 hoặc x=1/3

d: \(\dfrac{2}{3}x-\dfrac{1}{2}x=\dfrac{5}{12}\)

nên 1/6x=5/12

hay x=5/2

23 tháng 7 2017

a) \(\left(x-3\right)^2\) = \(\left(-3\right)^2\) + \(\left(-4\right)^2\)

\(\left(x-3\right)^2=9+16\)

\(\left(x-3\right)^2=25\)

\(\left(x-3\right)^2=5^2\)

\(\Rightarrow x-3=5\)

\(\Rightarrow x=5+3=8\)

Vậy x = 8

23 tháng 7 2017

b) -12 . (x - 5) +7 . (3 - x) = 5

-12x + 60 + 21 - 7x = 5

-12x - 7x = 5 - 60 - 21

-19x = -76

x = -76 : (-19) =4

Vậy x = 4

17 tháng 8 2017

a) -12.(x-5)+7.(3.x)=5

<=> -12x+60+21+7x=5

<=>-5x+81=5

<=>-5x=5-81=-76

<=>x=-76/-5=76/5=15,2

b) 30.(x+2)-6.(x-5)-24.x=100

<=> 30x+60-6x+30-24x=100

<=> 0x=100-60-30=10

=> không có giá trị nào của x để 0x=10

c) \(|5.x-2|< 13\)

Khi 5x-2 < 13

<=> 5x<15 <=> x<3

Khi 5x-2 <-13

<=> 5x<-11 <=> x<-11/5 <=> x<-2,2

25 tháng 6 2017

\(\frac{2}{3}\) .\(\frac{3}{4}\)\(\le\)\(\frac{x}{18}\) \(\le\)\(\frac{7}{3}\).\(\frac{1}{3}\)

\(\frac{1}{2}\le\frac{x}{18}\le\frac{7}{9}\)

\(\frac{9}{18}\le\frac{x}{18}\le\frac{14}{18}\)

\(\Rightarrow x\in\){9:10;11;12;13;14}

25 tháng 6 2017

\(\frac{2}{3}.\left(\frac{1}{2}+\frac{3}{4}-\frac{1}{3}\right)\le\frac{x}{18}\le\frac{7}{3}.\left(\frac{1}{2}-\frac{1}{6}\right)\)

\(\frac{2}{3}.\left(\frac{5}{4}-\frac{1}{3}\right)\le\frac{x}{18}\le\frac{7}{3}.\frac{1}{3}\)

\(\frac{2}{3}.\frac{11}{12}\le\frac{x}{18}\le\frac{7}{9}\)

\(\frac{11}{18}\le\frac{x}{18}\le\frac{7}{9}\)

\(\frac{11}{18}\le\frac{x}{18}\le\frac{14}{18}\)

Vậy \(x\in\left\{11;12;13\right\}\)

2 tháng 5 2017

a) \(\dfrac{2}{3}x-\dfrac{3}{2}x=\dfrac{5}{12}\)

\(x\left(\dfrac{2}{3}-\dfrac{3}{2}\right)=\dfrac{5}{12}\)

\(x\cdot\left(-\dfrac{5}{6}\right)=\dfrac{5}{12}\)

\(x=\dfrac{5}{12}:\left(-\dfrac{5}{6}\right)\)

\(x=-\dfrac{1}{2}\)

Vậy \(x=-\dfrac{1}{2}\).

b) \(\dfrac{2}{5}+\dfrac{3}{5}\cdot\left(3x-3\cdot7\right)=-\dfrac{53}{10}\)

\(\dfrac{3}{5}\left(3x-3\cdot7\right)=-\dfrac{53}{10}-\dfrac{2}{5}\)

\(\dfrac{3}{5}\left(3x-3\cdot7\right)=-\dfrac{57}{10}\)

\(3x-3\cdot7=-\dfrac{57}{10}:\dfrac{3}{5}\)

\(3x-3\cdot7=-\dfrac{19}{2}\)

\(3x-21=-\dfrac{19}{2}\)

\(3x=-\dfrac{19}{2}+21\)

\(3x=\dfrac{23}{2}\)

\(x=\)\(\dfrac{23}{2}:3\)

\(x=\dfrac{23}{6}\)

Vậy \(x=\dfrac{23}{6}\).

c) \(\dfrac{7}{9}:\left(2+\dfrac{3}{4x}\right)+\dfrac{5}{3}=\dfrac{23}{27}\)

\(\dfrac{7}{9}:\left(2+\dfrac{3}{4x}\right)=\dfrac{23}{27}-\dfrac{5}{3}\)

\(\dfrac{7}{9}:\left(2+\dfrac{3}{4x}\right)=-\dfrac{22}{27}\)

\(2+\dfrac{3}{4x}=\dfrac{7}{9}:-\dfrac{22}{27}\)

\(2+\dfrac{3}{4x}=-\dfrac{21}{22}\)

\(\dfrac{3}{4x}=-\dfrac{21}{22}-2\)

\(\dfrac{3}{4x}=-\dfrac{65}{22}\)

\(4x=\dfrac{3\cdot22}{-65}\)

\(4x=-\dfrac{66}{65}\)

\(x=-\dfrac{66}{65}:4\)

\(x=-\dfrac{33}{130}\)

Vậy \(x=-\dfrac{33}{130}\).

d) \(-\dfrac{2}{3}x+\dfrac{1}{5}=\dfrac{3}{10}\)

\(-\dfrac{2}{3}x=\dfrac{3}{10}-\dfrac{1}{5}\)

\(-\dfrac{2}{3}x=\dfrac{1}{10}\)

\(x=\dfrac{1}{10}:-\dfrac{2}{3}\)

\(x=-\dfrac{3}{20}\)

Vậy \(x=-\dfrac{3}{20}\).

e) \(\left|x\right|-\dfrac{3}{4}=\dfrac{5}{3}\)

\(\left|x\right|=\dfrac{5}{3}+\dfrac{3}{4}\)

\(\left|x\right|=\dfrac{29}{12}\)

\(x=\dfrac{29}{12}\) hoặc \(=-\dfrac{29}{12}\)

Vậy \(x\in\left\{\dfrac{29}{12};-\dfrac{29}{12}\right\}\).

25 tháng 3 2020
https://i.imgur.com/9YAi91S.jpg
29 tháng 1 2020

Cái này dễ mà, nên tự làm đi 😂😂😂