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b: \(\Leftrightarrow x+8\in\left\{1;-1;5;-5\right\}\)
hay \(x\in\left\{-7;-9;-3;-13\right\}\)
Bài 1:
a: \(x=\dfrac{2}{3}:\dfrac{3}{5}=\dfrac{2}{3}\cdot\dfrac{5}{3}=\dfrac{10}{9}\)
b: \(x=\dfrac{17}{8}:\dfrac{7}{17}=\dfrac{17}{8}\cdot\dfrac{17}{7}=\dfrac{289}{56}\)
c: \(x=-\dfrac{3}{4}:\dfrac{7}{12}=\dfrac{-3}{4}\cdot\dfrac{12}{7}=\dfrac{-63}{28}=-\dfrac{9}{4}\)
d: \(\Leftrightarrow x\cdot\dfrac{1}{6}=\dfrac{3}{8}-\dfrac{1}{4}=\dfrac{1}{4}\)
hay \(x=\dfrac{1}{4}:\dfrac{1}{6}=\dfrac{3}{2}\)
e: \(\Leftrightarrow\dfrac{1}{2}:x=-4-\dfrac{1}{3}=-\dfrac{17}{3}\)
hay \(x=-\dfrac{1}{2}:\dfrac{17}{3}=\dfrac{-3}{34}\)
a: =>x=-7/6+5/8=-13/24
b: =>x=-14/25-3/4=-131/100
c: \(x=\dfrac{-33}{26}:\dfrac{-9}{13}=\dfrac{33}{26}\cdot\dfrac{13}{9}=\dfrac{11}{3}\cdot\dfrac{1}{2}=\dfrac{11}{6}\)
d: \(x=\dfrac{4}{9}:\dfrac{5}{3}=\dfrac{4}{9}\cdot\dfrac{3}{5}=\dfrac{12}{45}=\dfrac{4}{15}\)
Bài 7:
a, \(x\) = \(\dfrac{1}{5}\) + \(\dfrac{2}{11}\)
\(x\) = \(\dfrac{11}{55}\) + \(\dfrac{10}{55}\)
\(x=\dfrac{21}{55}\)
b, \(\dfrac{x}{15}\) = \(\dfrac{3}{5}\) - \(\dfrac{2}{3}\)
\(\dfrac{x}{15}\) = \(\dfrac{9}{15}\) - \(\dfrac{10}{15}\)
\(\dfrac{x}{15}\) = \(\dfrac{1}{15}\)
\(x\) = 1
c, \(\dfrac{11}{8}\) + \(\dfrac{13}{6}\)= \(\dfrac{85}{x}\)
\(\dfrac{33}{24}\) + \(\dfrac{52}{24}\) = \(\dfrac{85}{x}\)
\(\dfrac{85}{24}\) = \(\dfrac{85}{x}\)
24 = \(x\)
Bài 1
a) (3x - 2⁴).7³ = 2.7⁴
3x - 16 = 2.7⁴ : 7³
3x - 16 = 2.7
3x - 16 = 14
3x = 14 + 16
3x =30
x = 30 : 3
x = 10
b) x - [42 + (-28)] = -8
x - 14 = -8
x = -8 + 14
x = 6
c) 4 - 7.x = x - (13 - 4)
x + 7x = 4 + 9
8x = 13
x = 13/8
Bài 1: a, (3\(x\) - 24 ).73 = 2.74
3\(x\) - 24 = 2.74 : 73
3\(x\) - 16 = 14
3\(x\) = 30
\(x\) = 10
b, \(x\) - (42 + (-28) ] = -8
\(x\) - 14 = -8
\(x\) = 14 - 8
\(x\) = 6
c, 4 - (7\(x\)) = \(x\) - (13 - 4)
4 - 7\(x\) = \(x\) - 9
\(x\) + 7\(x\) = 4 + 9
8\(x\) = 13
\(x\) = \(\dfrac{13}{8}\)
a) \(x:\dfrac{6}{13}=\dfrac{13}{7}\\ \Rightarrow x=\dfrac{13}{7}.\dfrac{6}{13}\\ \Rightarrow x=\dfrac{6}{7}\)
b) \(\dfrac{4}{7}.x-\dfrac{2}{3}=\dfrac{1}{5}\\ \Rightarrow\dfrac{4}{7}.x=\dfrac{13}{15}\\ \Rightarrow x=\dfrac{91}{60}\)
c) \(\left(\dfrac{3}{10}-x\right):\dfrac{2}{5}=\dfrac{3}{5}\\ \Rightarrow\dfrac{3}{10}-x=\dfrac{6}{25}\\ \Rightarrow x=\dfrac{3}{50}\)
d) \(\dfrac{2}{3}x-\dfrac{7}{6}=\dfrac{5}{2}\\ \Rightarrow\dfrac{2}{3}x=\dfrac{11}{3}\\ \Rightarrow x=\dfrac{11}{2}\)
a,-4/7=x/21
-12/21 = x/21
x= -12
b,(x-3)/15=1/-5
x - 3 = -1/5 * 15
x - 3 = -3
x = 0
c,.(3x+8)/-12=-5/30
=> 3x + 8 = 2
=> 3x=-6
=>x=-2
\(a,x+\frac{1}{2}=\frac{3}{4}.\frac{8}{6}\)
\(x+\frac{1}{2}=1\)
\(x=\frac{1}{2}\)
\(b,x-\left(\frac{1}{6}+\frac{1}{3}\right)=\frac{5}{2}.\frac{7}{5}\)
\(x-\frac{1}{6}-\frac{1}{3}=\frac{7}{2}\)
\(x-\frac{1}{6}=\frac{23}{6}\)
\(x=4\)
Câu c,d đâu