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\(a,\Leftrightarrow x=7-4=3\\ b,\Leftrightarrow2x=-18+5=-13\\ \Leftrightarrow x=-\dfrac{13}{2}\\ c,\Leftrightarrow x-21=10\\ \Leftrightarrow x=31\\ d,\Leftrightarrow-12-x+19=0\\ \Leftrightarrow7-x=0\\ \Leftrightarrow x=7\)
a, <=> x=7-4
<=> x=3
b, 2x= -18 +5
<=>2x=-13
<=> x= -13/2
c, <=> x -21=-10
<=> x= -10 +21
<=> x=11
d, <=> -12+19 -x=0
<=> 7-x=0
<=> x=7
Bài 2
a. 25-|x|=10
|x| =25-10
|x|=15
Vậy x=15 hoặc x=-15
sorry mk chưa làm được câu tiếp theo
b, |x-2|+7=12
|x-2| = 12-7
|x-2| = 5
+) Nếu x-2=5 thì x=7
+) Nếu x-2=-5 thì x=-3
a) Ta có: \(x-12=\left(-9\right)-15\)
\(\Rightarrow x-12=-24\)
\(\Rightarrow x=-12\)
b) \(2-x=17-\left(-5\right)\)
\(\Rightarrow2-x=22\)
\(\Rightarrow x=2-22\)
\(\Rightarrow x=-20\)
c) \(11-\left(15+11\right)=x-\left(25-9\right)\)
\(\Rightarrow-15=x-16\)
\(\Rightarrow x=1\)
d) \(x-\left(17-x\right)=x-7\)
\(\Rightarrow x-17+x=x-7\)
\(\Rightarrow x+x-x=-7+17\)
\(\Rightarrow x=10\)
e) \(9-25=\left(7-x\right)-\left(25+7\right)\)
\(\Rightarrow9-25=7-x-25-7\)
\(\Rightarrow-16=-25-x\)
\(\Rightarrow x=-9\)
g) \(x-13=21-x\)
\(\Rightarrow x+x=21+13\)
\(\Rightarrow2x=34\)
\(\Rightarrow x=17\)
a, x - 12 = ( -9 ) - 15
x - 12 = -24
x = -24 + 12
x = -12
b, 2 - x = 17 - ( -5 )
2 - x = 22
x = 2 - 22
x = -20
c, 11 - ( 15 + 11 ) = x - ( 25 - 9 )
11 - 26 = x - 16
-15 = x - 16
x = -15 + 16
x = 1
d, x - ( 17 - x ) = x - 7
x - 17 + x = x - 7
x + x - 17 = x - 7
x + x - x = -7 + 17
x = 10
e.9 - 25 = ( 7- x ) - ( 25 + 7 )
-16 = ( 7 - x ) -32
7 - x = -32 + 16
7 - x = 16
x = 7 - 16
x= -9
g, x - 13 = 21 - x
x + x = 21 + 13
2x = 44
x = 44 : 2
x=22
`Answer:`
a. \(x+12=3\Leftrightarrow x=3-12\Leftrightarrow x=-9\)
b. \(2x-15=21\Leftrightarrow2x=21+15\Leftrightarrow2x=36\Leftrightarrow x=36:2\Leftrightarrow x=18\)
c. \(13-3x=4\Leftrightarrow-3x=4-13\Leftrightarrow-3x=-9\Leftrightarrow x=-9:-3\Leftrightarrow x=3\)
d. \(2\left(x-2\right)+4=12\Leftrightarrow2x-4+4=12\Leftrightarrow2x=12\Leftrightarrow x=12:2\Leftrightarrow x=6\)
e. \(15-3\left(x-2\right)=21\Leftrightarrow15-3x+6=21\Leftrightarrow-3x=21-15-6\Leftrightarrow-3x=0\Leftrightarrow x=0\)
g. \(25+4\left(3-x\right)=1\Leftrightarrow25+12-4x=1\Leftrightarrow37-4x=1\Leftrightarrow-4x=-36\Leftrightarrow x=9\)
h. \(3x+12=2x-4\Leftrightarrow3x-2x=-4-12\Leftrightarrow x=-16\)
i. \(14-3x=\left(-x\right)+4\Leftrightarrow-3x+x=4-14\Leftrightarrow-2x=10\Leftrightarrow x=5\)
k. \(2\left(x-2\right)+7=x-25\Leftrightarrow2x-4+7=x-25\Leftrightarrow2x-x=-25-3\Leftrightarrow x=-28\)
a) \(x+5=20-\left(12-7\right)\)
\(\Rightarrow x+5=20-5\)
\(\Rightarrow x+5=15\)
\(\Rightarrow x=15-5\)
\(\Rightarrow x=10\)
b) \(15-\left(3+2x\right)=2^2\)
\(\Rightarrow3+2x=15-4\)
\(\Rightarrow3+2x=11\)
\(\Rightarrow2x=11-3\)
\(\Rightarrow2x=8\)
\(\Rightarrow x=\dfrac{8}{2}\)
\(\Rightarrow x=4\)
c) \(-11-\left(19-x\right)=50\)
\(\Rightarrow19-x=-11-50\)
\(\Rightarrow19-x=-61\)
\(\Rightarrow x=61+19\)
\(\Rightarrow x=80\)
d) \(159-\left(25-x\right)=43\)
\(\Rightarrow25-x=159-43\)
\(\Rightarrow25-x=116\)
\(\Rightarrow x=25-116\)
\(\Rightarrow x=-91\)
e) \(\left(79-x\right)-43=-\left(17-52\right)\)
\(\Rightarrow\left(79-x\right)-43=52-17\)
\(\Rightarrow79-x-43=35\)
\(\Rightarrow36-x=35\)
\(\Rightarrow x=1\)
f) \(\left(7+x\right)-\left(21-13\right)=32\)
\(\Rightarrow7+x-8=32\)
\(\Rightarrow x-1=32\)
\(\Rightarrow x=32+1\)
\(\Rightarrow x=33\)
g) \(-x+20=-15+8+13\)
\(\Rightarrow-x+20=6\)
\(\Rightarrow x=20-6\)
\(\Rightarrow x=14\)
h) \(-\left(-x+13-142\right)+18=55\)
\(\Rightarrow x-13+142+18=55\)
\(\Rightarrow x+147=55\)
\(\Rightarrow x=55-147\)
\(\Rightarrow x=-92\)
a, => x = 5 - 13 = -8
b, => x = -9 + 1 = -8
c, => |x| = 25 - 10 = 15
=> x = 15 hoặc x = -15
d, => |x-2| = 12 - 7 = 5
=> x-2 =5 hoặc x-2 = -5
=> x=7 hoặc x=-3