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a) 15 - (25 - x) = 2x - 17
15 - 25 + x = 2x - 17
x - 2x = -17 - 15 + 25
-x = -7
x = 7
b) 42 - (12 - x) = 2x - 15
42 - 12 + x = 2x - 15
x - 2x = -15 - 42 + 12
-x = -45
x = 45
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2.(x-5)-3.(x-4)=-6+15.-3
\(2\left(x-5\right)-3\left(x-4\right)=-51\)
\(\left(2x-10\right)-\left(3x-12\right)=-51\)
\(2x-10-3x+12=-51\)
\(\left(2x-3x\right)+\left(-10+12\right)=-51\)
\(-x+2=-51\)
\(-x=-53\)
\(x=53\)
vậy x=53
chúc bạn học tốt like mình nha
6x+42y⋮31
=> 6x+11y+31y⋮31
Vì 31y⋮31⇒6x+11y⋮31
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![Wink ;) ;)](http://diendan.hocmai.vn/styles/default/xenforo/clear.png)
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a) 50 : (x - 7) + 12 = 17
50 : (x - 7) = 17 - 12
50 : (x - 7) = 5
(x - 7) = 50 : 5
(x - 7) = 10
x = 10 + 7
\(\Rightarrow\) x = 17
b) 96 - 3 (x + 1) =42
3 (x + 1) = 96 - 42
3 (x + 1) = 54
(x + 1) = 54 : 3
(x + 1) = 18
x = 18 - 1
\(\Rightarrow\) x = 17
c) 63 : (x - 31) + 100 = 107
63 : (x - 31) = 107 - 100
63 : (x - 31) = 7
x - 31 = 63 : 7
x - 31 = 9
x = 9 + 31
\(\Rightarrow\) x = 40
CHÚC BẠN HOK TỐT
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\(x-\left[\frac{50x}{100}+\frac{25x}{200}\right]=11\frac{1}{4}\)
\(x-\left[\frac{50x\cdot2}{200}+\frac{25x}{200}\right]=11\frac{1}{4}\)
\(x-\left[\frac{100x}{200}+\frac{25x}{200}\right]=11\frac{1}{4}\)
\(x-\frac{125x}{200}=11\frac{1}{4}\)
\(\frac{200x}{200}-\frac{125x}{200}=11\frac{1}{4}\)
\(\frac{200x-125x}{200}=11\frac{1}{4}\)
\(\frac{75x}{200}=11\frac{1}{4}\)
\(\frac{3x}{8}=11\frac{1}{4}\)
\(3x=11\frac{1}{4}\cdot8\)
\(3x=90\)
\(x=30\)
Vậy x = 30
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1) Do x chia hết cho 15, x chia hết cho 25
=> x \(\in\)BC ( 15;25 )
Mà \(15=3.5\)
\(25=5^2\)
=> BCNN ( 15,25 ) = \(5^2.3=75\)
=> BC ( 15;25 ) = B ( 75 ) = { 0 ; 75 ; 150 ; 225 ; ...}
Mà 75 < x < 200
=> x = { 75 ; 150 }
2) Do 35 chia hết cho x
42 chia hết cho x
=> x \(\in\)ƯC ( 35;42 )
Mà \(35=5.7\)
\(42=2.3.7\)
=> UCLN ( 35,42 ) = 7
=> UC ( 35;42 ) = Ư ( 7 ) = { - 7 ; -1 ; 1 ; 7 }
Mà x > 1
=> x = { 1 ; 7 }
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\(a,\)\(9-25=\left(7-x\right)-\left(25+7\right)\)
\(-16=\left(7-x\right)-32\)
\(7-x=-16+32\)
\(7-x=16\)
\(x=7-16=-9\)
\(b,-7624+\left(1543+7624\right)-x=25\)
\(-7624+9167-x=25\)
\(1543-x=25\)
\(x=1543-25\)
\(x=1518\)
\(c,\left(27-514\right)-\left(486-73\right)+x=7\)
\(-487-413+x=7\)
\(-900+x=7\)
\(x=7+900\)
\(x=907\)
5 nhaaa
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