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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
1. Thực hiện phép tính bằng cách hợp lí :
a) (-46) + (-125) + 46 + 25 = [(-46)+46] + [(-125)+25]
= 0+(-100) = -100
b) 25.(-15) + 25.(-5) + (-20).75 = 25.[(-15)+(-5)] + (-20).75
= 25.(-20) + (-20).75 = (-20).(25+75) = (-20).100 = -2000
c) (-151)+(-37)+(-42)+(-63)+142 =(-151)+[(-37)+(-63)]+[(-42)+142]
= (-151) + [(-100) + 100] = -151
d)32+(-149)+(-311)+(-89)+(-51) = 32+[(-149)+(-51)] + [(-311)+(-89)]
= 32+[(-200)+(-400)] = 32+(-600) = -568
e)-65.(87-17)-87.(17-65) = (-65).87 - (-65).17 - 87.17 + 87.65
= (-65).87 + 65.17 - 87.17 + 87.65 = [(-65).87+87.65] + 65.(17-87)
= 65.(-70) = -4550
g) -43.(53-16) - 53.(16-43) = (-43).53 - (-43).16 - 53.16 + 53.43
= (-43).53 + 43.16 - 53.16 + 53.43 = [(-43).53+53.43] + 16.(43-53)
= 16.(-10) = -160
Câu 1:
a: =>-2x-x+17=34+x-25
=>-3x+17=x+9
=>-4x=-8
hay x=2
b: =>17x+16x+27=2x+43
=>33x+27=2x+43
=>31x=16
hay x=16/31
c: =>-2x-3x+51=34+2x-50
=>-5x+51=2x-16
=>-7x=-67
hay x=67/7
e: 3x-32>-5x+1
=>8x>33
hay x>33/8
a, 2.x + 7 = 15
2x = 8
x = 4
b, 25 – 3.(6 – x) = 22
3.(6-x) = 3
6-x = 1
x = 5
c, [(2x – 11) : 3 + 1].5 = 20
(2x-11) : 3+1 = 4
(2x-11):3 = 3
2x-11 = 1
2x = 12
x = 6
e, 2 . 3x = 10 . 312 + 8 . 274
6x = 3120 + 2192
6x = 5312
x = 5312/6
g, x – 12 = (–8) + (–17)
x - 12 = -25
x = -13
Lần sau tách nhỏ nội dung câu hỏi ra nha em, chứ trả lời thế này biếng lắm '^^ Chị làm chỉ mang tính tham khảo kết quả thôi, còn cụ thể thì em tách từng bước một ra he :>
a, \(2\cdot x+7=15\)
\(\Leftrightarrow2\cdot x=8\)
\(\Leftrightarrow x=4\)
Vậy x = 4.
b, \(25-3\cdot\left(6-x\right)=22\)
\(\Leftrightarrow3\cdot\left(6-x\right)=3\)
\(\Leftrightarrow6-x=1\)
\(\Leftrightarrow x=5\)
Vậy x = 5.
c, \(\left[\left(2x-11\right):3+1\right]\cdot5=20\)
\(\Leftrightarrow\left(2x-11\right):3+1=4\)
\(\Leftrightarrow\left(2x-11\right):3=3\)
\(\Leftrightarrow2x-11=9\)
\(\Leftrightarrow2x=20\)
\(\Leftrightarrow x=10\)
Vậy x = 10.
d, \(\left(25-2x\right)\cdot3:5-32=42\)
\(\Leftrightarrow\)\(\frac{3\cdot\left(25-2x\right)}{5}=74\)
\(\Leftrightarrow3\cdot\left(25-2x\right)=370\)
\(\Leftrightarrow25-2x=\frac{370}{3}\)
\(\Leftrightarrow2x=-\frac{295}{3}\)
\(\Leftrightarrow x\approx49\)
Vậy \(x\approx49\) .
e, \(2\cdot3x=10\cdot312+8\cdot274\)
\(\Leftrightarrow6x=5312\)
\(\Leftrightarrow x=5312:6\approx885\)
Vậy \(x\approx885\) .
g, \(x-12=\left(-8\right)+\left(-17\right)\)
\(\Leftrightarrow x-12=-25\)
\(\Leftrightarrow x=-25+12=-13\)
Vậy x = -13.
h, \(7-2x=18-3x\)
\(\Leftrightarrow-2x+3x=18-7\)
\(\Leftrightarrow x=11\)
Vậy \(x=11\) .
i, \(3\cdot\left(x+5\right)-x-11=24\)
\(\Leftrightarrow3x+15-x-11=24\)
\(\Leftrightarrow2x=24+11-15\)
\(\Leftrightarrow2x=20\)
\(\Leftrightarrow x=10\)
Vậy \(x=10\) .
A , 3 - ( 17 - x ) = 289 - ( 36 + 289 )
3 - 17 + x = 0 - 36
-14 + x = -36
x = -36 - ( - 14 ) = -22
B, 25 - ( x + 5 ) = -415 - ( 15 - 415 )
25 - x - 5 = 0 - 15
20 - x = -15
x = 20 - ( - 15 ) = 35
C , 34 + ( 21 - x ) = ( 3747 - 30 ) - 3746
34 + 21 - x = 1 - 30
55 - x = -29
x = 55 - (-29 ) = 74
D , -2x - ( x -17 ) = 34 - ( -x + 25 )
- 2x - x + 17 = 34 - 25 + x
- 3x + 17 = 9 + x
- 3x - x = 9 - 17
-4x = -8
x = -8 : ( - 4 )
x = 2
E , 17x + ( -16x - 37 ) = x + 43
17x - 16x -37 = x + 43
x - 37 = x + 43
-37 - 43 = x - x
- 80 = 0 ( vô lý )
G , ( x + 12 ) . (x - 3 ) = 0
\(\hept{\begin{cases}x+12=0\\x-3=0\end{cases}}\)
\(\hept{\begin{cases}x=-12\\x=3\end{cases}}\)
a ) \(5.\left(x-7\right)=0\)
\(\Leftrightarrow x-7=5.0\)
\(\Leftrightarrow x-7=0\)
\(\Leftrightarrow x=7\)
b ) \(34.\left(2.x-6\right)=0\)
\(\Leftrightarrow2.x-6=34.0\)
\(\Leftrightarrow2.x-6=0\)
\(\Leftrightarrow2.x=0+6\)
\(\Leftrightarrow2.x=6\)
\(\Leftrightarrow x=6\div2\)
\(\Leftrightarrow x=3\)
c ) \(25+\left(15-x\right)=30\)
\(\Leftrightarrow25+\left(15-x\right)=-\left(x-40\right)\)
\(\Leftrightarrow-\left(x-40\right)=2.3.5\)
\(\Leftrightarrow40-x=30\)
\(\Leftrightarrow-x=-10\)
\(\Leftrightarrow x=10\)
d ) \(43-\left(24-x\right)=20\)
\(\Leftrightarrow24-x=43-20\)
\(\Leftrightarrow24-x=23\)
\(\Leftrightarrow x=24-23\)
\(\Leftrightarrow x=1\)
e ) \(2.\left(x-5\right)-17=25\)
\(\Leftrightarrow2.\left(x-5\right)=25+17\)
\(\Leftrightarrow2.\left(x-5\right)=42\)
\(\Leftrightarrow x-5=42\div2\)
\(\Leftrightarrow x-5=21\)
\(\Leftrightarrow x=21+5\)
\(\Leftrightarrow x=26\)
f ) \(24+3.\left(5-x\right)=27\)
\(\Leftrightarrow3.\left(5-x\right)=27-24\)'
\(\Leftrightarrow3.\left(5-x\right)=3\)
\(\Leftrightarrow5-x=3\div3\)
\(\Leftrightarrow5-x=1\)
\(\Leftrightarrow x=5-1\)
\(\Leftrightarrow x=4\)
g ) \(15\div x-2=3\)
\(\Leftrightarrow15\div x=3+2\)
\(\Leftrightarrow15\div x=5\)
\(\Leftrightarrow x=15\div5\)
\(\Leftrightarrow x=3\)
h ) \(\left(32-x\div5\right)\div13=2\)
\(\Leftrightarrow32-x\div5=2\times13\)
\(\Leftrightarrow32-x\div5=26\)
\(\Leftrightarrow x\div5=32-26\)
\(\Leftrightarrow x\div5=6\)
\(\Leftrightarrow x=5.6\)
\(\Leftrightarrow x=30\)
g ) \(\left(6-2x\right)\left(x-8\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}6-2x=0\\x-8=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=8\end{matrix}\right.\)
Vậy \(x\in\left\{3;8\right\}\)
Mình làm hết nhaa !!
a)5.(x-7)=0
x-7=0:5
x-7=0
x=0+7
x=7
Vậy x=7
b)34.(2x-6)=0
2x-6 =0:34
2x-6 =0
2x=0+6
2x=6
x=6:2
x=3
Vậy x= 3
c)25+(15-x)=30
15-x=30-25
15-x=5
x=15-5
x=10
Vậy x=10
d)43-(24-x)=20
24-x =43-20
24-x=23
x=24-23
x=1
vậy x=1
e)2(x-5)-17=25
2(x-5)=25+17
2(x-5)=42
x-5=42:2
x-5=21
x=21+5
x=26
Vậy x=26
f)24+3(5-x)=27
3(5-x)=27-24
3(5-x)=3
5-x =3:3
5-x=1
x=5-1
x=4
Vậy x=4
g)15:x-2=3
15:x=3+2
15:x=5
x=15:5
x=3
Vậy x=3
h)( 32-x:5):13=2
32-x:5 =2.13
32-x :5=26
x:5= 32-26
x:5=6
x=6.5
x=30
Vậy x=30
k)(6-2x)(x-8)=0
➩6-2x=0 hoặc x-8=0
2x=6-0 x=0+8
2x=6 x=8
x=6:2
x=3
Vậy x=3 hoặc x=8