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1) x - 43 = (35 - x) - 48
=> x + x = 35 - 48 + 43
=> x + x = 30
=> x = 30 : 2
=> x = 15
2) 305 - x + 14 = 48 + (x + 23)
=> 305 - x + 14 = 48 + x + 23
=> -x - x = 48 + 23 - 14 - 305
=> -x - x = -248
=> -x = -248 : 2
=> -x = -124
=> x = 124
3) - (x - 6 + 85) = (x + 51) - 54
=> -x + 6 - 85 = x + 51 - 54
=> -x - x = 51 - 54 + 85 - 6
=> -x - x = 76
=> -x = 76 : 2
=> -x = 38
=> x = -38
4) - (35 - x - 37 - x) = 33 - x
=> -35 + x + 37 + x = 33 - x
=> x + x + x = 33 + 35 - 37
=> x + x + x = 31
=> x = 31 : 3
=> x \(=\dfrac{31}{3}\)
Vì x \(\in\) Z nên không có giá trị x nào thỏa mãn trong câu này.
5) 13 - | x | = | -4 |
=> 13 - |x| = 4
=> |x| = 13 - 4
=> |x| = 9
=> \(\left[{}\begin{matrix}x=9\\x=-9\end{matrix}\right.\)
6) | x | - 3 + 6 = 16
=> |x| = 16 - 6 + 3
=> |x| = 13
=> \(\left[{}\begin{matrix}x=13\\x=-13\end{matrix}\right.\)
7) 35 - | 2x - 1 | = 14
=> |2x - 1| = 35 - 14
=> |2x - 1| = 21
=> \(\left[{}\begin{matrix}2x-1=21\\2x-1=-21\end{matrix}\right.=>\left[{}\begin{matrix}2x=21+1\\2x=-21+1\end{matrix}\right.=>\left[{}\begin{matrix}2x=22\\2x=-20\end{matrix}\right.=>\left[{}\begin{matrix}x=22:2\\x=-20:2\end{matrix}\right.=>\left[{}\begin{matrix}x=11\\x=-10\end{matrix}\right.\)
8) | 3x - 2 | + 5 = 9 - x
=> |3x - 2| = 9 - 5 - x
=> |3x - 2| = 4 - x
=> \(\left[{}\begin{matrix}3x-2=4-x\\3x-2=x-4\end{matrix}\right.=>\left[{}\begin{matrix}3x+x=4+2\\3x-x=-4+2\end{matrix}\right.=>\left[{}\begin{matrix}4x=6\\2x=-2\end{matrix}\right.=>\left[{}\begin{matrix}x=6:4\\x=-2:2\end{matrix}\right.=>\left[{}\begin{matrix}x=\dfrac{6}{4}\\x=-1\end{matrix}\right.\)
Vì x \(\in\) Z nên x = -1.
9) x - ( -25 + 7 ) > 12 - ( 15 - 14 )
=> x - (-18) > 12 - 1
=> x + 18 > 11
=> x > 11 - 18
=> x > -7
10) | 17 + ( x - 15 ) | < 4
=> \(\left[{}\begin{matrix}17+\left(x-15\right)< 4\\17+\left(x-15\right)< -4\end{matrix}\right.=>\left[{}\begin{matrix}x-15< 4-17\\x-15< -4-17\end{matrix}\right.=>\left[{}\begin{matrix}x-15< -15\\x-15< -21\end{matrix}\right.=>\left[{}\begin{matrix}x< -15+15\\x< -21+15\end{matrix}\right.=>\left[{}\begin{matrix}x< 0\\x< -6\end{matrix}\right.=>x< -6\)
11) x2 - 5x = 0
=> x . (2 - 5) = 0
=> x . (-3) = 0
=> x = 0 : (-3)
=> x = 0
12) | x-9 | . (-8) = -16
=> |x - 9| = (-16) : (-8)
=> |x - 9| = 3
=> \(\left[{}\begin{matrix}x-9=3\\x-9=-3\end{matrix}\right.=>\left[{}\begin{matrix}x=3+9\\x=-3+9\end{matrix}\right.=>\left[{}\begin{matrix}x=12\\x=6\end{matrix}\right.\)
13) | 4 - 5x | = 24 với x < hoặc = 0
=> \(\left[{}\begin{matrix}4-5x=24\\4-5x=-24\end{matrix}\right.=>\left[{}\begin{matrix}5x=4-24\\5x=4-\left(-24\right)\end{matrix}\right.=>\left[{}\begin{matrix}5x=-20\\5x=28\end{matrix}\right.=>\left[{}\begin{matrix}x=-20:5\\x=28:5\end{matrix}\right.=>\left[{}\begin{matrix}x=-4\\x=\dfrac{28}{5}\end{matrix}\right.\)
Vì x \(\le\) 0 nên x = -4
14) x . ( x - 2 ) > 0
=> \(\left[{}\begin{matrix}\left\{{}\begin{matrix}x>0\\x-2>0\end{matrix}\right.\\\left\{{}\begin{matrix}x< 0\\x-2< 0\end{matrix}\right.\end{matrix}\right.=>\left[{}\begin{matrix}\left\{{}\begin{matrix}x>0\\x>2\end{matrix}\right.\\\left\{{}\begin{matrix}x< 0\\x< 2\end{matrix}\right.\end{matrix}\right.=>\left[{}\begin{matrix}x>2\\x< 2\end{matrix}\right.\)
15) x . ( x - 2 ) < 0
=> \(\left[{}\begin{matrix}\left\{{}\begin{matrix}x< 0\\x-2>0\end{matrix}\right.\\\left\{{}\begin{matrix}x>0\\x-2< 0\end{matrix}\right.\end{matrix}\right.=>\left[{}\begin{matrix}\left\{{}\begin{matrix}x< 0\\x>2\end{matrix}\right.\\\left\{{}\begin{matrix}x>0\\x< 2\end{matrix}\right.\end{matrix}\right.=>\left[{}\begin{matrix}2>x< 0\left(loại\right)\\0< x< 2\left(chọn\right)\end{matrix}\right.=>0< x< 2\)
16) (x-1) . (y+1) = 5
=> \(\left[{}\begin{matrix}x-1=5\\y+1=1\end{matrix}\right.=>\left[{}\begin{matrix}x=5+1\\y=1-1\end{matrix}\right.=>\left[{}\begin{matrix}x=6\\y=0\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}x-1=1\\y+1=5\end{matrix}\right.=>\left[{}\begin{matrix}x=1+1\\y=5-1\end{matrix}\right.=>\left[{}\begin{matrix}x=2\\y=4\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}x-1=-1\\y+1=-5\end{matrix}\right.=>\left[{}\begin{matrix}x=-1+1\\y=-5-1\end{matrix}\right.=>\left[{}\begin{matrix}x=0\\y=-6\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}x-1=-5\\y+1=-1\end{matrix}\right.=>\left[{}\begin{matrix}x=-5+1\\y=-1-1\end{matrix}\right.=>\left[{}\begin{matrix}x=-4\\y=-2\end{matrix}\right.\)
17) x . ( y +2 ) = -8
=> \(\left[{}\begin{matrix}x=1\\y+2=-8\end{matrix}\right.=>\left[{}\begin{matrix}x=1\\y=-8-2\end{matrix}\right.=>\left[{}\begin{matrix}x=1\\y=-10\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}x=-1\\y+2=8\end{matrix}\right.=>\left[{}\begin{matrix}x=-1\\y=8-2\end{matrix}\right.=>\left[{}\begin{matrix}x=-1\\y=4\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}x=-8\\y+2=1\end{matrix}\right.=>\left[{}\begin{matrix}x=-8\\y=1-2\end{matrix}\right.=>\left[{}\begin{matrix}x=-8\\y=-1\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}x=8\\y+2=-1\end{matrix}\right.=>\left[{}\begin{matrix}x=8\\y=-1-2\end{matrix}\right.=>\left[{}\begin{matrix}x=8\\y=-3\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}x=2\\y+2=-4\end{matrix}\right.=>\left[{}\begin{matrix}x=2\\y=-4-2\end{matrix}\right.=>\left[{}\begin{matrix}x=2\\y=-6\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}x=-2\\y+2=4\end{matrix}\right.=>\left[{}\begin{matrix}x=-2\\y=4-2\end{matrix}\right.=>\left[{}\begin{matrix}x=-2\\y=2\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}x=4\\y+2=-4\end{matrix}\right.=>\left[{}\begin{matrix}x=4\\y=-4-2\end{matrix}\right.=>\left[{}\begin{matrix}x=4\\y=-6\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}x=-4\\y+2=2\end{matrix}\right.=>\left[{}\begin{matrix}x=-4\\y=2-2\end{matrix}\right.=>\left[{}\begin{matrix}x=-4\\y=0\end{matrix}\right.\)
18) xy - 2x - 2y = 0
=> x . (y - 2) - 2y = 0
=> x . (y - 2) - 2y - 4 = -4
=> x . (y - 2) - 2 . (y - 2) = -4
=> (y - 2) . (x - 2) = -4
=> \(\left[{}\begin{matrix}y-2=1\\x-2=-4\end{matrix}\right.=>\left[{}\begin{matrix}y=1+2\\x=-4+2\end{matrix}\right.=>\left[{}\begin{matrix}y=3\\x=-2\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}y-2=-1\\x-2=4\end{matrix}\right.=>\left[{}\begin{matrix}y=-1+2\\x=4+2\end{matrix}\right.=>\left[{}\begin{matrix}y=1\\x=6\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}y-2=2\\x-2=-2\end{matrix}\right.=>\left[{}\begin{matrix}y=2+2\\x=-2+2\end{matrix}\right.=>\left[{}\begin{matrix}y=4\\x=0\end{matrix}\right.\)
hoặc
=> \(\left[{}\begin{matrix}y-2=-2\\x-2=2\end{matrix}\right.=>\left[{}\begin{matrix}y=-2+2\\x=2+2\end{matrix}\right.=>\left[{}\begin{matrix}y=0\\x=4\end{matrix}\right.\)
19) 2x - 5 \(⋮\) x - 1
=> (2x - 2) - (5 - 2) \(⋮\) x - 1
=> 2(x - 1) - 3 \(⋮\) x - 1
Vì 2(x - 1) \(⋮\) x - 1 nên 3 \(⋮\) x - 1
=> x - 1 \(\in\) Ư(3) = {-3; -1; 1; 3}
=> x \(\in\) {-2; 0; 2; 4}
P/s: Mình không bảo đảm là đúng hết nên câu nào sai thì bạn thông cảm nha~
1.
a. 727-(182+727)=727-182-727=(727-727)+182=182
b.(258-79)-(121-142)=258-79-121+42=(258+42)-(79+121)=300-200=100
c.2016-(391+2016)-9=2016-391-2016-9=(2016-2016)-(391+9)=0-400=-400
d.15.12-3.3.10=15.12-15.10=15(12-10)=15.2=30
e.45-9(13+5)=45-9.13-9.15=45-117-45=-117
g.29(19-13)-19(29-13)=29.19-29.13-19.29+19.13=(29.19-19.29)+(19.13-29.13)=13(19-29)=13.(-10)=-130
2)
a. 4(x+1)-(3x-1)=14
4x+4-3x+1=14
x+5=14=>x=9
b. (x^2-9)(x+2)=0
=>x^2-9=0 hoặc x+2=0
=>x\(\in\){+3;-2}
c. ((x^2+9)(2x-4)=0
=>x^2+9=0 hoặc 2x-4=0
=>x^2=-9 hoặc 2x=4
vì x^2\(\ge\)0 với mọi x=>x^2\(\ne\)9
=>2x=4=>x=2
d. mk chịu
Bạn Mai ngọc câu 1a bạn trả lời bị sai , kết quả của nó là - 182 . Và câu 1b của bạ hình như cũng bị sai vì mik hỏi banj mik thì kết quả của bọn nó = 200 . Nhưng mik rất cảm ơn bạn đã giải giúp mik nên mik tặng bạn **** . Mấy bạn khác có câu trả lời đúng chính xác sẽ được nhìu **** thôi , nếu các bạn khác đúng mik sẽ đăng nhập nick khác để **** cho các bạn . Khi làm bài các bạn vui lòng ghi rõ ra cho mik nha .
a) \(\dfrac{2}{3}x-\dfrac{1}{2}=\dfrac{1}{10}\)
\(\dfrac{2}{3}x=\dfrac{1}{10}+\dfrac{1}{2}=\dfrac{3}{5}\)
\(x=\dfrac{3}{5}:\dfrac{2}{3}=\dfrac{9}{10}\)
b) \(\dfrac{39}{7}:x=13\)
\(x=\dfrac{\dfrac{39}{7}}{13}=\dfrac{3}{7}\)
c) \(\left(\dfrac{14}{5}x-50\right):\dfrac{2}{3}=51\)
\(\dfrac{14}{5}x-50=51\cdot\dfrac{2}{3}=34\)
\(\dfrac{14}{5}x=34+50=84\)
\(x=\dfrac{84}{\dfrac{14}{5}}=30\)
d) \(\left(x+\dfrac{1}{2}\right)\left(\dfrac{2}{3}-2x\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{2}=0\\\dfrac{2}{3}-2x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=\dfrac{1}{3}\end{matrix}\right.\)
e) \(\dfrac{2}{3}x-\dfrac{1}{2}x=\dfrac{5}{12}\)
\(\dfrac{1}{6}x=\dfrac{5}{12}\)
\(x=\dfrac{5}{12}:\dfrac{1}{6}=\dfrac{5}{2}\)
g) \(\left(x\cdot\dfrac{44}{7}+\dfrac{3}{7}\right)\dfrac{11}{5}-\dfrac{3}{7}=-2\)
\(\left(x\cdot\dfrac{44}{7}+\dfrac{3}{7}\right)\cdot\dfrac{11}{5}=-2+\dfrac{3}{7}=-\dfrac{11}{7}\)
\(x\cdot\dfrac{44}{7}+\dfrac{3}{7}=-\dfrac{11}{7}:\dfrac{11}{5}=-\dfrac{5}{7}\)
\(\dfrac{44}{7}x=-\dfrac{5}{7}-\dfrac{3}{7}=-\dfrac{8}{7}\)
\(x=-\dfrac{8}{7}:\dfrac{44}{7}=-\dfrac{2}{11}\)
h) \(\dfrac{13}{4}x+\left(-\dfrac{7}{6}\right)x-\dfrac{5}{3}=\dfrac{5}{12}\)
\(\dfrac{25}{12}x-\dfrac{5}{3}=\dfrac{5}{12}\)
\(\dfrac{25}{12}x=\dfrac{5}{12}+\dfrac{5}{3}=\dfrac{25}{12}\)
\(x=1\)
Mỏi tay woa bn làm nốt nha!!
a)4x+4-3x+1=14
x+5=14
x=11
b)trường hợp 1 x2-9=0
x2=9
->x=3;-3
-trường hợp 2: x+2=0
x=-2
c)-th1:x2+9=0
x2=-9
->x rỗng
d)xy+2x-y-2=0
(xy-y)+(2x-2)=0
y(x-1)+2(x-1)=0
(y+2)(x-1)=0
th1: y+2=0
y=-2
th2:x-1=0
x=1
(th1: trường hợp 1)
a)-16+23+x=-16
7+x=-16
x=-16-7
x=-23
b)2.x-35=15
2.x=15+35
2.x=50
x=50:2
x=25
c)3.x+17=12
3.x=12-17
3.x=-5
x=-5:3
x=-1,(6)
d)Ix-1I=0
IxI=0+1
IxI=1
=>x=1 hoặc x=-1
e)-13.IxI=-26
IxI=-26:(-13)
IxI=2
=>x=2 hoặc x=-2

a, -3x=-12 => x= 4
b, x(x+1)=0 => x=0 hoặc x=-1
a) -3x=-12
=>x=-12:-3
=>x=4
b)x(x+1)=0
=>\(\orbr{\begin{cases}x=0\\x+1=0\end{cases}}\) <=>\(\orbr{\begin{cases}x=0\\x=-1\end{cases}}\)
c)13-|x|=|-4|
=>13-|x|=4
=>x=9 hoặc x=-9 (|-9|=|9|)
d) 35-|2x-1|=14
=>2x-1=21
=>x=11
hay x=-11 (vô lí)
\(\left|6-2x\right|+\left|y+9\right|=0\)
Ta có \(\left|6-2x\right|\ge0\forall x;\left|y+9\right|\ge0\forall y\)
\(\Rightarrow\left|6-2x\right|+\left|y+9\right|\ge0\forall x,y\)
\(\Rightarrow\left|6-2x\right|+\left|y+9\right|=0\)
\(\Leftrightarrow\hept{\begin{cases}6-2x=0\\y+9=0\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}x=3\\y=-9\end{cases}}\)