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a) x-28:7=16
x-4=16
x=16+4
x=20
Vậy x=20
b)3x-63=930:928
3(x-21)=81
x-21=27
x=21+27
x=48
Vậy x=48
a, x-28:7=16
x-4=16
x=16+4
x=20
b, 3x-63=9^30:9^28
3x-63=9^2
3x-63=81
3x=81+63
3x=144
x=144:3
x=48
1)
a)
\(\frac{-5}{6}.\frac{120}{25}< x< \frac{-7}{15}.\frac{9}{14}\)
\(\frac{-1}{1}.\frac{20}{5}< x< \frac{-1}{5}.\frac{3}{2}\)
\(\frac{-20}{5}< x< \frac{-3}{10}\)
\(\frac{-40}{10}< x< \frac{-3}{10}\)
\(\Rightarrow Z\in\left\{-4;-5;-6;-7;-8;-9;-10;...;-39\right\}\)
\(a\)) \(\frac{x-1}{3}=\frac{4}{2}=2\)
\(x-1=2\times3=6\)
\(x=6+1=7\)
b) \(\left(\frac{3x}{7}+1\right):4=-\frac{1}{28}\)
\(\frac{3x}{7}+1=-\frac{1}{28}\times4=-\frac{1}{7}\)
\(\frac{3x}{7}=-\frac{1}{7}-1=-\frac{8}{7}\)
\(3x=\left(-\frac{8}{7}\right)\times7=-8\)
\(x=-\frac{8}{3}\)
c) \(\frac{2x}{4}=\frac{9}{2}\)
\(2x=\frac{9}{2}\times4\)
\(2x=18\)
\(x=18:2=9\)
a, \(\frac{x-1}{3}=\frac{4}{2}=2\)
\(\Rightarrow x-1=2.3\)
\(x-1=6\)
\(x=6+1\)
\(x=7\)
a) \(\left(\frac{3x}{7}+1\right):\left(-4\right)=\frac{-1}{28}\)
\(\Rightarrow\frac{3}{7}.x+1=\frac{-1}{28}.\left(-4\right)\)
\(\Rightarrow\frac{3}{7}.x=\frac{1}{7}-1\)
\(\Rightarrow\frac{3}{7}.x=\frac{-6}{7}\)
\(\Rightarrow x=\frac{-6}{7}:\frac{3}{7}\)
\(\Rightarrow x=\frac{-6}{7}.\frac{7}{3}\)
\(\Rightarrow x=-2\)
b) x+30%x=-1.3 mình coi 1.3 là 1,3 nhé !
\(\Rightarrow x\left(30\%+1\right)=-1,3\)
\(\Rightarrow x\left(\frac{13}{10}\right)=-\frac{13}{10}\)
\(\Rightarrow x=-\frac{13}{10}:\frac{13}{10}\)
\(\Rightarrow x=-1\)
a) y = 28.(-9):21 = -12
Thế y vào ta có: x = 6.28:(-12) = -14
Vậy x = -14, y = -12
b) Ta có: 5/6+(-2/3).1/5 = 7/10
x = 7.30:10 = 21
Vậy x = 21
dễ ợt
Bài 1:
a) x + 1919 - 3535 = 3636 b) 3434 - x + 611611 = 5656
x + 1919 = 3636 + 3535 3434 - x = 5656 - 611611
x + 1919 = 11101110 3434 - x = 19661966
x = 11101110 - 1919 x = 19661966 + 3434
x = 89908990 x = 137132137132
Bài 2
a) x : 13/16 = 5/8 b)x - 14/28 = 6/9 + 8/25
x = 5/8 * 13/16 x - 14/28 = 74/75
x = 65/128 x = 74/75 + 14/28
x = 223/150
Bài 3
a)62/7 * x = 29/9 : 3/56 b)1/5 : x = 1/5 + 1/7
62/7 * x = 1624/27 1/5 : x = 12/35
x = 1624/27 : 62/7 x = 12/35 * 1/5
x = 5684/637 x = 12/175
0,5x-2/3x=7/12
=>(1/2-2/3).x=7/12
=>-1/6x=7/12
=>x=7/12:1/6
=>x=7/2
b, x:4 1/3=-2,5
=>x:13/3=-2,5
=>x=-5/2x13/3
=>x=-13
c,5,5x=13/15
=>11/2x=13/15
=>x=13/15:11/2
=>x=26/165
d,(3x/7+1):-4=-1/28
=>3x/7+1=-1/28x(-4)
=>3x/7+1=-1/7
=>3x/7=-1/7-1
=>3x/7=-8/7
=>3x=-8/7x7
=>3x=8
=>x=8:3
=>x=8/3
\(0,5x-\frac{2}{3}x=\frac{7}{12}\)
\(\frac{1}{2}x-\frac{2}{3}x=\frac{7}{12}\)
\(\left(\frac{1}{2}-\frac{2}{3}\right)x=\frac{7}{12}\)
\(\frac{-1}{6}x=\frac{7}{12}\)
\(x=-21\)
b,c,d tương tự
a) x - 28 : 7 = 16
x - 4 = 16
x = 16 + 4
x = 20
b) 3x - 63 = 930 : 928
3x - 63 = 92
3x - 63 = 81
3x = 81 - 63
3x = 18
x = 18 : 3
x = 6