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-1/2 .x + 2/3 : (-4/5) = 3/5 - 5/6
-1/2.x - 5/6 = -7/30
-1/2.x = -7/30 + 5/6
-1/2.x = 3/5
x = 3/5 : (-1/2)
x = 6/5
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Lời giải:
a.
$\frac{2}{3}x-\frac{7}{6}=\frac{12}{7}-\frac{1}{2}=\frac{17}{14}$
$\frac{2}{3}x=\frac{17}{14}+\frac{7}{6}=\frac{50}{21}$
$x=\frac{50}{21}: \frac{2}{3}=\frac{25}{7}$
b.
$(1\frac{1}{2}+\frac{5}{3}-\frac{1}{6}):x=\frac{3}{4}-\frac{1}{2}$
$3:x=\frac{1}{4}$
$x=3: \frac{1}{4}=12$
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5)
để \(\frac{5x-3}{x+1}\)là số nguyên
\(5x-3⋮x+1\)
\(x+1⋮x+1\)
\(\Rightarrow5\left(x+1\right)⋮x+1\)
\(5x-3-\left(5x-5\right)⋮x+1\)
\(-2⋮x+1\)
\(\Rightarrow x+1\inƯ\left(2\right)=\left\{\pm1;\pm2\right\}\)
x+1 | 1 | -1 | 2 | -2 |
x | 0 | -2 | 1 | -3 |
Vậy \(x\in\left\{0;-2;1;-3\right\}\)
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Câu 1:
a) \(\frac{3}{2}.\frac{4}{5}-x=\frac{2}{3}\)
\(\frac{6}{5}-x=\frac{2}{3}\)
\(x=\frac{8}{15}\)
b) \(\frac{6}{7}:\frac{1}{2}.\frac{3}{4}-\frac{5}{8}=\frac{37}{56}\)
Câu 2:
Gọi số có hai chữ số cần tìm là: ab
ta có: ab2 = ab + 92
=> a x 100 + b x 10 + 2 = a x 10 + b + 92
=> a x 90 + b x 9 = 90
9 x ( a x 10 + b) = 90
a x 10 + b = 90 : 9
a x 10 + b = 10 = 1 x 10 + 0
=> a = 1; b = 0
KL: ab = 10
Câu 1 :
a) \(\frac{3}{2}\times\frac{4}{5}-x=\frac{2}{3}\)
\(\Rightarrow\frac{6}{5}-x=\frac{2}{3}\)
\(\Rightarrow x=\frac{6}{5}-\frac{2}{3}\)
\(\Rightarrow x=\frac{8}{15}\)
b) Ko rõ đề :)
Câu 2 :
Gọi số cần tìm là \(\overline{ab}\), ta có :
\(\overline{ab2}-\overline{ab}=92\)
\(\Rightarrow\overline{ab}\times10+2-\overline{ab}=92\)
\(\Rightarrow\overline{ab}\times9+2=92\)
\(\Rightarrow\overline{ab}\times9=90\)
\(\Rightarrow\overline{ab}=90:9\)
\(\Rightarrow\overline{ab}=10\)
Học tốt # ^-<
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1: =>5(2x+6)=40
=>2x+6=8
=>2x=2
=>x=1
2: =>12-(x+3)=256:64=4
=>(x+3)=8
=>x=5
3: =>2x-1=3 hoặc 2x-1=-3
=>x=2 hoặc x=-1
4: \(\Leftrightarrow3^{x+2017}=3^{2015}\)
=>x+2017=2015
=>x=-2
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Ta có : a, 3/2 * 4/5 - x = 2/3 .
=> 6/5 - x = 2/3 .
=> 6/5 - 2/3 = x .
=> 18/15 - 10/15 = x .
=> x = 8/15 .
b, 6/7 : 1/2 * 3/4 - 5/8 = 12/7 * 3/4 - 5/8 .
= 9/7 - 5/8 .
= 72/56 - 35/56 .
= 37/56 .
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X + 1 + 1 + 1 + 1 + 2 + 2 + 2 + 3 + 3 + 3 + 3 + 4 + 4 + 4 + 5 + 5 + 5 + 6 + ( -6 ) = 500
X + 49 = 500
X = 500 - 49
X = 451
k minh nhe minh tra loi nhanh nhat , dung nhat va day du nhat
b,(2+x):5=6
2+x=6.5=30
x=30-2=28
c,2x-3=11
2x=11+3=14
x=14:2=7
d,2+x:5=6
x:5=6-2=4
x=4.5=20
b) (2 + x) : 5 = 6
2 + x = 6 × 5
2 + x = 30
x = 30 - 2
x = 28
Vậy x = 28
c) 2 × x - 3 = 11
2 × x = 11 + 3
2 × x = 14
x = 14 : 2
x = 7
Vậy x = 7
d) 2 + x : 5 = 6
x : 5 = 6 - 2
x : 5 = 4
x = 4 × 5
x = 20
Vậy x = 20