Bài 7: x E Z
a) 3 - x = ( - 21 ) - ( - 9 )
b) x - 15 = 17 - 48
c) x + 25 = 63 - ( -17 )
d) 2x - 15 = ( - 11 ) - ( -16 )
e) (- 7 ) - 2x = ( - 37 ) - ( -26 )
g) Ix+ 9I - 3 = 0
h) 15 . Ix -6I = 60
i) 3 .IxI =12 : 4
Bài 2:
a,x-2=-6-5x-16
b,-5x-[-3]-x=13-x
c,15-[x-7]=-21-x
d,3x+17=2+3x+15
e,x-45-[x-9]=-35-x
f,[-5]+x=15-x-2x
g,2x-[-17]=15
a)x-2=6-5x-16
6x= -8
x= -4/3
b)-5x-(-3)-x=13-x
-5x+3-x=13-x
-5x=10
x=-2
c)15-(x-7)=-21-x
15-x+7=-21-x
22=-21 ( vô lí)
x không có giá trị
D)3x+17=2+3x+15
17=17
x có vô số giá trị
e) x-45-(x-9)=-35-x
x-45-x+9=-35-x
-x=1
x=-1
f) -5+x=15-x-2x
4x=20
x=5
g) 2x-(-17) =15
2x+17=15
2x=-2
x=-1
Bài 1: Tìm x nguyên, biết:
a) x + 5 = 20 - (12 -7)
b)15 - (3+ 2x) = 22
c) -11 - (19 - x) = 50
d)159 - (25 - x) = 43
e) (79 - x) - 43 = - (17 - 52)
f) (7 + x) - (21 - 13) = 32
g) - x + 20 = (-15) + 8 + 13
h) - (-x + 13 -142) + 18 = 55
Xin cảm ơn!
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) \(-\left(-x+13-142\right)+18=55\)
\(\Rightarrow x-13+142+18=55\)
\(\Rightarrow x+147=55\)
\(\Rightarrow x=55-147\)
\(\Rightarrow x=-92\)
Bài 8: tìm x
a) x + 10 = 20
b) 2 . x + 15 = 35
c) 3 ⋅ ( x + 2 ) = 15
d) 10 . x + 15 . 11 = 20 . 10
e) 4 . ( x + 2 ) = 3 . 4
f) 33 x + 135 = 26 . 9
g) 2 . x + 15 + 16 + 17 = 100
h) 2 . (x + 9 + 10 + 11) = 4 . 12 . 25
`@` `\text {Ans}`
`\downarrow`
`a)`
`x + 10 = 20`
`=> x = 20 -10`
`=> x = 10`
Vậy, `x = 10`
`b)`
`2 * x + 15 = 35`
`=> 2x = 35 - 15`
`=> 2x = 20`
`=> x = 20 \div 2`
`=> x = 10`
Vậy, `x = 10`
`c)`
`3 * ( x + 2 ) = 15`
`=> x + 2 = 15 \div 3`
`=> x + 2 = 5`
`=> x = 5 - 2`
`=> x = 3`
Vậy, `x = 3`
`d)`
`10 * x + 15 * 11 = 20 * 10`
`=> 10x + 165 = 200`
`=> 10x = 200 - 165`
`=> 10x = 35`
`=> x = 35 \div 10`
`=> x = 3,5`
Vậy,` x = 3,5`
`e)`
`4 * ( x + 2 ) = 3 * 4`
`=> x + 2 = 12 \div 4`
`=> x + 2 = 3`
`=> x = 3 - 2`
`=> x = 1`
Vậy,` x = 1`
`f)`
`33 x + 135 = 26 * 9`
`=> 33x + 135 = 234`
`=> 33x = 234 - 135`
`=> 33x = 99`
`=> x = 99 \div 33`
`=> x = 3`
Vậy, `x = 3`
`g)`
`2 * x + 15 + 16 + 17 = 100`
`=> 2x + 48 = 100`
`=> 2x = 100 - 48`
`=> 2x = 52`
`=> x = 52 \div 2`
`=> x =26`
`h)`
`2 * (x + 9 + 10 + 11) = 4 . 12 . 25`
`=> 2 * (x + 9 + 10 + 11) = 4*25*12`
`=> 2 * (x + 9 + 10 + 11) = 100*12`
`=> x + 9 + 10 + 11 = 100*12 \div 2`
`=> x + 30 = 600`
`=> x = 600 - 30`
`=> x = 570`
Vậy, `x = 570.`
a) \(x+10=20\Leftrightarrow x=10\)
b) \(2x+15=35\Leftrightarrow2x=20\Leftrightarrow x=10\)
c) \(3.\left(x+2\right)=15\Leftrightarrow x+2=5\Leftrightarrow x=3\)
d) \(10x+15.11=20.10\Leftrightarrow10x+165=200\Leftrightarrow10x=35\Leftrightarrow x=\dfrac{35}{10}=\dfrac{7}{2}\)
e) \(4.\left(x+2\right)=3.4\Leftrightarrow x+2=3\Leftrightarrow x=1\)
f) \(35x+135=26.9\Leftrightarrow35x=234-135\Leftrightarrow35x=99\Leftrightarrow x=\dfrac{99}{35}\)
g) \(2x+15+16+17=100\Leftrightarrow2x+48=100\Leftrightarrow2x=52\Leftrightarrow x=26\)
h) \(2.\left(x+9+10+11\right)=4.12.25\)
\(\Leftrightarrow x+30=2.12.25\)
\(\Leftrightarrow x=600-30\)
\(\Leftrightarrow x=570\)
Bài 1 Tính:
a) 75-5.(15-10)-(-60)
b) 136-(-7)+6-23-36
c) (-15-17).(-15+7)
d) (-9-18):(-9)
Bìa 2 Tìm x:
a) 2x-17=(-3x-18)
b) (13-IxI) +15=20
c) Ix+5I-(x+5)=0
a, 75 - 5 . ( 15 - 10 ) - ( -60 ) = 75 - 5 . 5 + 60 = 135 - 25 = 110
b, 136 - ( -7 ) + 6 - 23 - 36 = 136 + 7 + 6 - 23 - 36 = ( 136 - 36 ) + ( 7 + 6 - 23 ) = 100 - 10 = 90
c, ( -15 - 17 ) . ( -15 + 7 ) = -32 . ( -8 ) = 256
d, ( -9 - 18 ) : ( -9 ) = -27 : ( -9 ) = 3
Bài 2:
a, 2x - 17 = ( -3x - 18 )
<=> 2x + 3x = 17 - 18
<=> 5x = -1
<=> x = -1/5
b, ( 13 - IxI ) + 15 = 20
<=> 13 - |x| = 5
<=> |x| = 8
<=> x = 8 hoặc x = -8
c, Ix + 5I - ( x + 5 ) = 0
<=> |x + 5| = x + 5
Đk: x + 5 ≥ 0 => x ≥ -5
\(\Leftrightarrow\orbr{\begin{cases}x+5=x+5\\x+5=-x-5\end{cases}\Leftrightarrow}\orbr{\begin{cases}0x=0\\2x=-10\end{cases}\Leftrightarrow}\orbr{\begin{cases}x\ge-5\\x=-5\end{cases}}\)
Vậy x ≥ -5
Tìm x biết:
a)-2x-17=-11
b)15-(7-2x)=-11-(-25)
c)43-(x+17)=-17-(-25)
d)-42/x/=-15
e)/x-2/-(-13)=17
g)-11</x/<3
a) -2x-17=-11 b)15-7+2x=-11+25 c) 43-x-17=-17+25
-2x=6 8+2x=14 26-x=8
x=-3 2x=6 x=18
x=3
d) -42|x|=-15 e)|x-2|+13=17 g)-11<|x|<3
|x| = + - 5/14 |x-2|=4 xl mk k biết làm câu này. bạn nào biết giải nốt giúp mk nha!
xét 2 trường hợp x>0 và x<0.
lần sau bạn có đăng bài dài như thế này thì bạn hãy chia ra làm 2 bài để m.n có hứng giải giúp bạn nha!
a) |x − 3| − 16 = −4
b) 26 - |x + 9| = −13
c) 5 – ( 10 – x) = 7
d) 11 + ( 15 –x) = 1
e) 8x – 75 = 5x + 21
f) 9x + 25 = - ( 2x – 58)
g) |x + 3| = 4
h) 15 - |2x − 1| = |−8|
a, \(\left|x-3\right|-16=-4\Leftrightarrow\left|x-3\right|=12\)
\(\Leftrightarrow\orbr{\begin{cases}x-3=12\\x-3=-12\end{cases}\Leftrightarrow\orbr{\begin{cases}x=15\\x=-9\end{cases}}}\)
b, \(26-\left|x+9\right|=-13\Leftrightarrow\left|x+9\right|=39\)
\(\Leftrightarrow\orbr{\begin{cases}x+9=39\\x+9=-39\end{cases}\Leftrightarrow\orbr{\begin{cases}x=30\\x=-48\end{cases}}}\)
f, \(9x+25=-\left(2x-58\right)\Leftrightarrow9x+25=-2x+58\)
\(\Leftrightarrow11x-33=0\Leftrightarrow x=3\)
Làm nốt nhé !
a. \(\left|x-3\right|-16=-4\)
\(\Rightarrow\left|x-3\right|=12\)
\(\Rightarrow\orbr{\begin{cases}x-3=12\\x-3=-12\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=15\\x=-9\end{cases}}\)
b. \(26-\left|x+9\right|=-13\)
\(\Rightarrow\left|x+9\right|=39\)
\(\Rightarrow\orbr{\begin{cases}x+9=39\\x+9=-39\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=30\\x=-48\end{cases}}\)
c. \(5-\left(10-x\right)=7\)
\(\Rightarrow10-x=-2\)
\(\Rightarrow x=12\)
d. \(11+\left(15-x\right)=1\)
\(\Rightarrow15-x=-10\)
\(\Rightarrow x=25\)
e. \(8x-75=5x+21\)
\(\Rightarrow8x-5x=75+21\)
\(\Rightarrow3x=96\)
\(\Rightarrow x=32\)
f. \(9x+25=-\left(2x-58\right)\)
\(\Rightarrow9x+25=-2x+58\)
\(\Rightarrow9x+2x=58-25\)
\(\Rightarrow11x=33\)
\(\Rightarrow x=3\)
g. \(\left|x+3\right|=4\)
\(\Rightarrow\orbr{\begin{cases}x+3=4\\x+3=-4\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=1\\x=-7\end{cases}}\)
h. \(15-\left|2x-1\right|=\left|-8\right|\)
\(\Rightarrow15-\left|2x-1\right|=8\)
\(\Rightarrow\left|2x-1\right|=7\)
\(\Rightarrow\orbr{\begin{cases}2x-1=7\\2x-1=-7\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=4\\x=-4\end{cases}}\)
a,\(|x-3|-16=-4\)
\(< =>|x-3|=-4+16\)
\(< =>|x-3|=12\)
\(< =>\orbr{\begin{cases}x-3=12\\x-3=-12\end{cases}< =>\orbr{\begin{cases}x=15\\x=-9\end{cases}}}\)
b, \(26-|x+9|=-13\)
\(< =>-|x+9|=-13-26\)
\(< =>|x+9|=39\)
\(< =>\orbr{\begin{cases}x+9=39\\x+9=-39\end{cases}< =>\orbr{\begin{cases}x=30\\x=-48\end{cases}}}\)
c, \(5-\left(10-x\right)=7\)
\(< =>5-10+x=7\)
\(< =>x=7+10-5=12\)
d, \(11+\left(15-x\right)=1\)
\(< =>11+15-x=1\)
\(< =>26-1=25=x\)
Tìm x,y biết
a,I2x-1I = Ix+3I
b,IxI+I2y-6I=0
c,Ix-2I>3
d,Ix-7I=x-7
e,I2x+6I-2x-6
a,-x + 8 = -17
b, 35 - x = 37
c, -19 -x = -20
d, x - 45 = -17
e, | x+ 3| = 15
g, |x-7| +13 = 25
f, |x-3| -16 = -4
k, 26 -| x+9| = -13
a) -x + 8 = -17
⇔ -x = -17 - 8
⇔ -x = -25
⇔ x = 25
b) 35 - x = 37
⇔ x = 35 - 37
⇔ x = -2
c) -19 - x = -20
⇔ x = -19 + 20
⇔ x = 1
d) x - 45 = -17
⇔ x = -17 + 45
⇔ x = 28
e) |x + 3| = 15
⇔ \(\left[{}\begin{matrix}x+3=15\\x+3=-15\end{matrix}\right.\)
⇔ \(\left[{}\begin{matrix}x=15-3\\x=-15-3\end{matrix}\right.\)
⇔ \(\left[{}\begin{matrix}x=12\\x=-18\end{matrix}\right.\)
f) |x - 3| - 16 = -4
⇔ |x - 3| = -4 + 16
⇔ |x - 3| = 12
⇔ \(\left[{}\begin{matrix}x-3=12\\x-3=-12\end{matrix}\right.\)
⇔ \(\left[{}\begin{matrix}x=12+3\\x=-12+3\end{matrix}\right.\)
⇔ \(\left[{}\begin{matrix}x=15\\x=-9\end{matrix}\right.\)
k) 26 - |x + 9| = -13
⇔ |x + 9| = 26 + 13
⇔ |x + 9| = 39
⇔ \(\left[{}\begin{matrix}x+9=39\\x+9=-39\end{matrix}\right.\)
⇔ \(\left[{}\begin{matrix}x=39-9\\x=-39-9\end{matrix}\right.\)
⇔ \(\left[{}\begin{matrix}x=30\\x=-48\end{matrix}\right.\)
a,-x + 8 = -17
=> -x=-17-8
=> -x=-25
=> x=25
vậy x=25
b, 35 - x = 37
=> x=35-37
=> x=-2
vậy x=-2
c, -19 -x = -20
=> x=-19+20
=> x=1
vậy x=1
d, x - 45 = -17
=> x=-17+45
=> x=28
vậy x=28
e, | x+ 3| = 15
th1 x+3=15
=> x=15-3
=> x=12
th2 x+3=-15
=> x=-15-3
=> x=-18
vậy x=12 hoặc x=-18
g, |x-7| +13 = 25
=> \(\left|x-7\right|=25-13\)
=> \(\left|x-7\right|=12\)
th1 x-7=12
=> x=12+7
=> x=19
th2 x-7=-12
=>x=-12+7
=> x=-5
vậy x=19 hoặc x=-5
các câu sau tt
g) |x - 7| + 13 = 25
⇔ |x - 7| = 25 - 13
⇔ |x - 7| = 12
⇔ \(\left[{}\begin{matrix}x-7=12\\x-7=-12\end{matrix}\right.\)
⇔ \(\left[{}\begin{matrix}x=12+7\\x=-12+7\end{matrix}\right.\)
⇔ \(\left[{}\begin{matrix}x=19\\x=-5\end{matrix}\right.\)
bài 19: tìm x
a) 5 . ( x - 7 ) = 0
b) 25 ( x - 4 ) = 0
c) ( 34 - 2x ) . ( 2x - 6 ) = 0
d) ( 2019 - x ) . ( 3x - 12 ) 0
e) 57 . ( 9x - 27 ) = 0
f) 25 + ( 15 - x ) = 30
g) 43 - ( 24 - x ) = 20
h) 2 . ( x - 5 ) - 17 = 25
i) 3 . ( x + 7 ) - 15 = 27
j) 15 + 4 . ( x - 2 ) = 95
k) 20 - ( x + 14 ) = 5
l) 14 + 3 . ( 5 - x ) = 27
a) \(5\left(x-7\right)=0\)
\(\Rightarrow x-7=0\)
\(\Rightarrow x=7\)
b) \(25\left(x-4\right)=0\)
\(\Rightarrow x-4=0\)
\(\Rightarrow x=4\)
c) \(\left(34-2x\right)\left(2x-6\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}34-2x=0\\2x-6=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}2x=34\\2x=6\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=17\\x=3\end{matrix}\right.\)
d) \(\left(2019-x\right)\left(3x-12\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}2019-x=0\\3x-12=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=2019\\3x=12\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=2019\\x=\dfrac{12}{3}=4\end{matrix}\right.\)
e) \(57\left(9x-27\right)=0\)
\(\Rightarrow9x-27=0\)
\(\Rightarrow9\left(x-3\right)=0\)
\(\Rightarrow x-3=0\)
\(\Rightarrow x=3\)
a) 5.(x-7)=0⇔x-7=0⇔x=7
b) 25(x-4)=0⇔x-4=0⇔x=4
c) (34-2x).(2x-6)=0
⇔ 34-2x=0 hoặc 2x-6=0
⇔2x=34 hoặc 2x=6
⇔ x=17 hoặc x=3
d) (2019-x).(3x-12)=0
⇔ 2019-x=0 hoặc 3x-12=0
⇔ x=2019 hoặc x=4
e) 57.(9x-27)=0
⇔ 9x-27=0
⇔ x=3
f) 25+(15-x)=30
⇔ 15-x=5
⇔ x=10
g) 43-(24-x)=20
⇔ 24-x=23
⇔ x=1
h) 2.(x-5)-17=25
⇔ 2(x-5)=42
⇔x-5=21
⇔ x=26
i) 3(x+7)-15=27
⇔ 3(x+7)=42
⇔ x+7=14
⇔ x=7
j) 15+4(x-2)=95
⇔ 4(x-2)=80
⇔ x-2=20
⇔ x=22
k) 20-(x+14)=5
⇔ x+14=15
⇔ x=1
l) 14+3(5-x)=27
⇔ 3(5-x)=13
⇔ 5-x=13/3
⇔ x=5-13/3
⇔ x=2/3