TÌM X 3/4+X/20=4/5
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Câu 6: Khôg có cau nào đúng
Câu 7: C
Câu 8: B
Câu 9: B
Câu 10: D
a: \(\Leftrightarrow\left|\dfrac{5}{3}x\right|=\dfrac{1}{6}\)
\(\Leftrightarrow\left[{}\begin{matrix}x\cdot\dfrac{5}{3}=\dfrac{1}{6}\\x\cdot\dfrac{5}{3}=-\dfrac{1}{6}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{6}:\dfrac{5}{3}=\dfrac{3}{30}=\dfrac{1}{10}\\x=-\dfrac{1}{10}\end{matrix}\right.\)
b: \(\Leftrightarrow\left|\dfrac{3}{4}x-\dfrac{3}{4}\right|=\dfrac{3}{4}+\dfrac{3}{4}=\dfrac{3}{2}\)
\(\Leftrightarrow\left|x-1\right|=\dfrac{3}{2}:\dfrac{3}{4}=2\)
=>x-1=2 hoặc x-1=-2
=>x=3 hoặc x=-1
c: \(\Leftrightarrow\left|x+\dfrac{3}{5}\right|=\left|x-\dfrac{7}{3}\right|\)
\(\Leftrightarrow x+\dfrac{3}{5}=\dfrac{7}{3}-x\)
=>2x=44/15
hay x=22/15
Bài 1:
a: x+1/2=5/6
nên x=5/6-1/2=1/3
b: x+1/4=3/4
nên x=3/4-1/4=2/4=1/2
c: x+3/10=1/2
nên x=1/2-3/10=5/10-3/10=1/5
d: x+1/4=3/8
nên x=3/8-1/4=3/8-2/8=1/8
a: x-4/5=3/7
=>x=3/7+4/5=43/35
b: x+3/7=4/5
=>x=4/5-3/7=13/35
c: 19/20-x=8/5-3/4
=>19/20-x=32/20-15/20=17/20
=>x=2/20=1/10
d: =>4/5*x=2/21
=>x=2/21:4/5=5/42
e: =>x:7/9=6/8
=>x=6/8*7/9=3/4*7/9=21/36=7/12
f: =>x/6=2/3-1/3=1/3
=>x=2
a: x-4/5=3/7
=>x=3/7+4/5=43/35
b: x+3/7=4/5
=>x=4/5-3/7=13/35
c: 19/20-x=8/5-3/4
=>19/20-x=32/20-15/20=17/20
=>x=2/20=1/10
d: =>4/5*x=11/21
=>x=55/84
e: =>x=6/8*7/9=42/72=7/12
f: =>x/6=2/3-1/3=1/3
=>x=2
a) 3 x 5 < 3 x 6
3 x 5 > 3x 4
b) 3 x 5 = 5 x 3
4 x 6 = 6 x 4
c) 20 : 4 > 20 : 5
20 : 4 < 20 : 2
\(\frac{x-3}{x+3}=\frac{3}{7}\Leftrightarrow\left(x-3\right).7=3.\left(x+3\right)\)
\(\Leftrightarrow7x-21=3x+9\Rightarrow7x-3x=9-\left(-21\right)\)
\(\Leftrightarrow4x=30;x=7,5\)
b) \(\frac{x+4}{20}=\frac{5}{x+4}\Leftrightarrow\left(x+4\right)\left(x+4\right)=5.20\)
\(x^2+\left(4+4\right)^2=100\)
\(x^2=100-64=36\)
\(\Rightarrow x\in\left\{-6;6\right\}\)
a: Ta có: \(60-3\left(x-2\right)=51\)
\(\Leftrightarrow3\left(x-2\right)=9\)
\(\Leftrightarrow x-2=3\)
hay x=5
b: Ta có: \(4x-20=2^5:2^3\)
\(\Leftrightarrow4x=24\)
hay x=6
`3/4 + x/20 = 4/5`
`=> x/20 = 4/5 - 3/4`
`=> x/20 = 16/20 - 15/20`
`=> x/20=1/20`
`=>x=1`