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góp ý nè
bạn nên đăng ít một thôi mk nghĩ sẽ nhiều người trả lời hơn đó ạ.
Như mk ý, dài như bài này mk ko giải âu
Bai 1:
a) (x - 6)2 = 9
(x - 6)2 = 32
=> x - 6 = 3
x = 3 + 6
x = 8
Vay x = 8
b) (2x - 130) : 4 + 213 = 52 + 193
(2x - 130) : 4 + 213 = 25 + 193
(2x - 130) : 4 + 213 = 218
(2x - 130) : 4 = 218 - 213
(2x - 130) : 4 = 5
(2x - 130) = 5 . 4
(2x - 130) = 20
2x = 20 + 130
2x = 150
x = 150 : 2
x = 75
Vay x = 75
c) | 3x - 15| = 0
=> 3x - 15 = 0
3x = 0 + 15
3x = 15
x = 15 : 3
x = 5
Vay x = 5
Bai 2:
a) (17 - 229) + ( 17 - 25 + 229)
= 17 - 229 + 17 - 25 + 229
= 17 + (-229) + 17 + (-25) + 229
= [ 229 + (-229) ] + [17 + 17 + (-25) ]
= 0 + 9
= 9
b) - (269 - 357) + (269 - 357)
= - 269 + 357 + 269 - 357
= - 269 + 357 + 269 + (-357)
= [ 269 + (-269) ] + [ 357 + (-357) ]
= 0 + 0
= 0
c) (125 - 679 + 145) - (125 - 679)
= 125 - 679 + 145 - 125 + 679
= 125 + (- 679) +145 + (-125) + 679
= [ 679 + (-679) ] + [ 125 + (-125) ] + 145
= 0 + 0 + 145
= 145
1a) 25 .8 - 12.5 + 272 :17 - 8
= 200 - 60 + 16 - 8
= 140+16-8
= 156 - 8
= 148
b) 125: 25 +14 - 142 : 71
= 5 + 14 - 2
= 19 - 2 = 17
c) 13. 17 - 256: 16 + 14 : 7 - 1
= 221 - 16 + 2 - 1
= 205 + 2 - 1
= 207 - 1 = 206
d) 15 . 24 - 14 . 5 (145 : 5 - 27)
= 360 - 70 (29- 27)
= 360 - 70 . 2
= 360 - 140
= 220
2a) 37 + x = 55
x= 55 - 37
x = 18
b) x- 31 = 24
x = 24 + 31
x = 55
c) 21 (x-11) = 21
x - 11 = 21 : 21
x = 1 +11
x = 12
d ) 9. (x - 29)= 0
x - 29 = 0 :9
x = 29
e) (x - 1954) . 5 = 50
x - 1954 = 50 : 5
x = 1964
f ) 30 . 60 - x = 30
1800 - x = 30
x = 1800 - 30
x = 1770
Viết mỏi tay quá huhuh
a,\(15-\left(-4-x\right)=6\)
\(\Leftrightarrow-4-x=15-6\)
\(\Leftrightarrow-4-x=9\)
\(\Leftrightarrow x=-4-9\)
\(\Leftrightarrow x=-13\)
b,\(-30+\left(25-x\right)=-1\)
\(\Leftrightarrow25-x=-1-\left(-30\right)\)
\(\Leftrightarrow25-x=29\)
\(\Leftrightarrow x=25-29=-4\)
c,\(x-\left(12-25\right)=-8\)
\(\Leftrightarrow x+13=-8\)
\(\Leftrightarrow x=-21\)
e,\(x-5=1\Rightarrow x=6\)
g,\(x+30=-4\)
\(\Leftrightarrow x=-4-30\)
\(\Leftrightarrow x=-34\)
h,\(x-\left(-24\right)=3\)
\(\Leftrightarrow x+24=3\)
\(\Leftrightarrow x=3-24\)
\(\Leftrightarrow x=-21\)
i,\(\left(x+5\right)+\left(x-9\right)=x+2\)
\(\Leftrightarrow x+5+x-9-x-2=0\)
\(\Leftrightarrow x-6=0\)
\(\Leftrightarrow x=6\)
k,\(\left(27-x\right)+\left(15+x\right)=x-24\)
\(\Leftrightarrow27-x+15+x-x+24=0\)
\(\Leftrightarrow-x+66=0\)
\(\Leftrightarrow-x=-66\)
\(\Leftrightarrow x=66\)
a) 15-(-4-x)=6
15 + 4 + x = 6
19 + x = 6
x = 6 - 19
x = 6 + ( -19 )
x = -13
b) -30+( 25- x ) =-1
25- x = -1 - ( - 30 )
25- x = -1 + 30
25- x =29
x = 25 - 29
x = 25 + ( -29 )
x = -4
c) x- ( 12-25) =-8
x - ( - 13 ) = -8
x + 13 = -8
x = -8 - 13
x = -8 + ( -13 )
x = - 21
d) ( x-29 ) - (17- 38 ) = -9
( x-29) - (-21 ) = -9
x -29 = -9 + ( -21 )
x -29 = -30
x = -30 + 29
x = -1
e) x-5=1
x = 1 + 5
x = 6
g) x + 30 = -4
x = -4 - 30
x = -4 + ( -30 )
x = -34
h) x- ( -24 ) = 3
x = 3 + ( -24 )
x = -21
l) 22- ( - x ) = 12
-x = 22 - 12
-x = 10
x = -10
i) ( x + 5 ) + ( x - 9 ) = x + 2
x + 5 + x - 9 = x + 2
x + x + ( 5 - 9 ) = x + 2
x + x + ( -4 ) = x + 2
x + x = x + 2 - ( -4 )
x + x = x + 2 + 4
x + x =x + 6
=> x = 6
1. Tìm x biết:
a) 15 – ( 4 – x) = 6
4-x=15-6
4-x=9
x=4-9
x=-5
b) - 30 + ( 25 – x) = - 1
25-x=-1-(-30)
25-x=29
x=25-29
x=-4
c) x – ( 12 – 25) = -8
x+13=-8
x=-8-13
x=-21
d) ( x – 29 ) – ( 17 – 38 ) = - 9
(x-29)-(-21)=-9
(x-29)=-9-21
x-29=-30
x=-30+29
x=-1
2. Tìm số nguyên x biết:
a) x – 5 = - 1
x=-1+5
x=4
b) x + 30 = - 4
x=-4-30
x=-34
c) x – ( - 24) = 3
x+24=3
x=3-24
x=-21
d) 22 – ( - x ) = 12
22+x=12
x=12-22
x=-10
e) ( x + 5 ) + ( x – 9 ) = x + 2
x+5+x-9=x+2
x+x-x=2-5+9
x=6
f) ( 27 – x ) + ( 15 + x ) = x – 24
27-x+15+x=x-24
-x+x+x=-24-27-15
x=-66
3. Tìm x biết:
a) 461 + (x - 45) = 387
x-45=387-461
x-45=-74
x=-74+45
x=-29
b) 11 - (-53+ x ) = 97
-53+x=11-97
-53+x=-86
x=-86-(-53)
x=-33
c) - ( x + 84) + 213 = -16
-(x+84)=-16-213
-(x+84)=-229
x+84=229
x=229-84
x=145
a) 25. (x-4) = 0
=> x -4 =0
x = 4
b) 43 - (24-x) = 20
43 - 24 + x = 20
19 + x = 20
x = 1
c) 3.(x+7) - 15 = 27
3.x + 21 - 15 = 27
3.x + 6 = 27
3.x = 21
x = 7
d)... bn ghi thiếu đề r
e) (2.x-6).(x-7) = 0
=> 2.x -6 = 0 => 2x = 6 => x = 3
x - 7 = 0 => x = 7
KL: x = 3 hoặc x = 7
phần d lm tương tự như phần f nha bn!
a,25(x-4)=0
x-4=0
x=4
b,43-(24-x)=20
43-24+x=20
x=1
c,3(x+7)-15=27
3x+21-15=27
3x=21
x=7
d,(x-4)(x-12)=0
x-4=0=>x=4
x-12=0=>x=12
e,(2x-6)(x-7)=0
2x-6=0=>x=3
x-7=0=>x=7
f,(5x-10)(2x-8)=0
5x-10=0=>x=2
2x-8=0=>x=2
a) (125 -679 + 145 ) - ( 125 - 679 )=125 -679+145-125+679=145
b)(x - 29 ) - ( 17 - 38 ) = -9
<=> x-29 -17+38=-9
<=>x=-1
c)( x + 5 ) + ( x - 9 ) = x + 2
<=>x+5+x-9=x+2
<=>x+x-x=2+9-5
<=>x=6
d) ( 27 - x )+ ( 15 + x ) = x - 24
<=> 27-x+15+x-x=-24
<=> -x=-66
<=>x=66
e) -359 + 181 + ( -123 ) + 350 + ( -172 ) = (181 +350)-(359+172) -123 =531-531-123=-123
f) 13 - 12 + 11 + 10 - 9 + 8 - 7 -6 + 5 - 4 + 3 + 2 -1=( 13 - 12) +11 + (10 - 9)+(8-7)-6+(5-4)+3+(2-1)=1+11+1+1-6+1+3+1=13
a, (125 -679 + 145 ) - ( 125 - 679 )
= 125 - 679 + 145 - 125 + 679
= ( 125 - 125 ) + ( -679 + 679 ) + 145
= 0 + 0 +145
= 145
b, (x - 29 ) - ( 17 - 38 ) = -9
x - 29 - 17 + 38 = -9
x - 29 - 17 = -9 - 38
x - 29 - 17 = -47
x - 29 = -47 + 17
x - 29 = -30
x = -30 + 29
x = -1
Vậy x = -1
c, ( x + 5 ) + ( x - 9 ) = x + 2
x + 5 + x - 9 = x + 2
x - x + 14 = x + 2
14 = x + 2
x = 14 - 2
x = 12
Vậy x = 12
d, ( 27 - x )+ ( 15 + x ) = x - 24
27 - x + 15 + x = x - 24
42 + ( -x + x ) = x - 24
42 = x - 24
x = 24 + 42
x = 66
Vậy x = 66
e, -359 + 181 + ( -123 ) + 350 + ( -172 )
= ( -359 + 350 ) + [ 181 + ( -172 ) ] + ( -123)
= (-9) + 9 + ( -123 )
= 0 + ( -123)
= (-123)
g , 13 - 12 + 11 + 10 - 9 + 8 - 7 -6 + 5 - 4 + 3 + 2 -1
= ( 13 - 12 ) + ( 10 - 9 ) + ( 8 - 7 ) + ( 5 - 4 ) + ( 2 - 1 ) + ( 11 - 6 + 3)
= 1 + 1 + 1 + 1 + 1 + 8
= 1. 5 + 8
= 5 + 8
= 13
a, Ta có : \(x-5=-1\)
\(\Leftrightarrow x=\left(-1\right)+5\)
\(\Rightarrow x=4\)
Vậy \(x=4\)
b, Ta có :\(x+30=-4\)
\(\Leftrightarrow\left(-4\right)-30\)
\(\Leftrightarrow x=\left(-34\right)\)
Vậy \(x=\left(-34\right)\)
c, Ta có : \(x-\left(-24\right)=3\)
\(x=3+\left(-24\right)\)
\(\Leftrightarrow x=\left(-21\right)\)
Vậy \(x=\left(-21\right)\)
d,Ta có : \(22-\left(-x\right)=12\)
\(\Leftrightarrow\left(-x\right)=22-12\)
\(\Leftrightarrow\left(-x\right)=10\)
Vậy ....