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a)x-63:9=18
x-63 =18.9
x-63 =162
x =162+63
x =225
b)3(29-x)+52=103
3(29-x) =103-52
3(29-x) =51
29-x =51:3
29-x =17
x =12
c)|x-1|=4
=>x-1=4 hoặc x-1= -4
=>x=5 hoặc x= -3
d)(-7)-x= -21
x=(-7)-(-21)
x=14
a) x-63;9=18
x-7=18
x=18+7=25
b)3(29-x)=103-52
87-3x=51
-3x=51-87=-36
x=12
c)
* x-1 =4
x=5
* x-1=-4
x=-3
d)(-7)-x=-21
-x=-21+7=14
x=14
a) 22+x=52
x=52-22
x=30
b) 2x-3=45
2x=45+3
2x=48
x=48:2
x=24
c)4x = 64
4x=43
\(\Rightarrow x=3\)
a, 71.2 – 6.(2x+5) = 10 5 : 10 3
71.2 – 6.(2x+5) = 10 2
6.(2x+5) = 71.2 – 100
6.(2x+5) = 42
x = 1
b, 5 x + 3 4 . 6 8 = 6 9 . 3 4
5 x + 3 4 . 6 8 = 6 8 . 6 . 3 4
5 x + 3 4 = 6 8 . 6 . 3 4 : 6 8 = 6 . 3 4
5x = 6 . 3 4 - 3 4 = 5 . 3 4
x = 3 4
c, 12:{390:[5. 10 2 – ( 5 3 + x . 7 2 )]} = 4
390:[5. 10 2 – ( 5 3 + x . 7 2 )] = 12:4 = 3
5. 10 2 – ( 5 3 + x . 7 2 ) = 390:3 = 130
5 3 + x . 7 2 = 5. 10 2 – 130 = 370
x . 7 2 = 370 – 5 3 = 245
x = 245: 7 2 = 5
d, 5 3 .(3x+2):13 = 10 3 : 13 5 : 13 4
5 3 .(3x+2):13 = 10 3 : 13
3x+2 = 10 3 : 13 : 5 3 .13 = 8
x = 2
a) 5 6 + 1 6 ≤ x ≤ 13 4 + 14 8 ⇔ 1 ≤ x ≤ 5 ⇔ x ∈ 1 ; 2 ; 3 ; 4 ; 5
b) − 5 6 + 8 3 + 29 − 6 ≤ x ≤ − 1 2 + 2 + 5 2 ⇔ − 3 ≤ x ≤ 4 ⇔ x ∈ − 3 ; − 2 ; − 1 ; 0 ; 1 ; 2 ; 3 ; 4
c) 79 15 + 7 5 + − 8 3 ≤ x ≤ 10 3 + 15 4 + 23 12 ⇔ 4 ≤ x ≤ 9 ⇔ x ∈ 4 ; 5 ; 6 ; 7 ; 8 ; 9
1)\(x=\left(\dfrac{1}{5}+\dfrac{2}{3}\right):\dfrac{4}{7}=\left(\dfrac{3}{15}+\dfrac{10}{15}\right):\dfrac{4}{7}=\dfrac{13}{15}:\dfrac{4}{7}=\dfrac{91}{60}\)
2)\(x=\left(-\dfrac{3}{10}-\dfrac{3}{4}\right):\dfrac{1}{2}=\left(-\dfrac{6}{20}-\dfrac{15}{20}\right):\dfrac{1}{2}=-\dfrac{21}{20}:\dfrac{1}{2}=-\dfrac{21}{10}\)
3)\(x=-\dfrac{24}{36}-\dfrac{7}{15}=-\dfrac{2}{3}-\dfrac{7}{15}=\dfrac{-10}{15}-\dfrac{7}{15}=-\dfrac{17}{15}\)
1) \(\dfrac{4}{7}x=\dfrac{1}{5}+\dfrac{2}{3}\)
\(\dfrac{4}{7}x=\dfrac{13}{15}\)
\(x=\dfrac{91}{60}\)
2) \(\dfrac{1}{2}x=-\dfrac{3}{10}-\dfrac{3}{4}\)
\(\dfrac{1}{2}x=-\dfrac{21}{20}\)
\(x=-\dfrac{21}{10}\)
3) \(x=-\dfrac{24}{36}-\dfrac{7}{15}\)
\(x=\dfrac{-2}{3}+\dfrac{7}{15}\)
\(x=-\dfrac{17}{15}\)
| 2x - 3 | + 4.52 = 103
| 2x - 3 | + 4.25 = 103
| 2x - 3 | + 100 = 103
| 2x - 3 | = 103 - 100
| 2x - 3 | = 3
=> 2x - 3 = 3 hoặc 2x - 3 = - 3
2x = 3 + 3 2x = -3 + 3
2x = 6 2x = 0
x = 6 : 2 x = 0 : 2
x = 3 x = 0
vậy .................
/2x-3/+4.25=103
=>/2x-3/+100=103
=>/2x-3/=103-100
=>/2x-3/=3
=>\(\orbr{\begin{cases}2x-3=3\\2x-3=-3\end{cases}\Rightarrow\orbr{\begin{cases}2x=6\\2x=0\end{cases}\Rightarrow}\orbr{\begin{cases}x=3\\x=0\end{cases}}}\)
Mik làm tắt
Bài 2: (2 điểm) Tìm x biết:
a) \(x-63\div9=18\)
\(\Rightarrow x-7=18\)
\(\Rightarrow x=25\)
Vậy \(x=25\)
b) \(3\left(29-x\right)+52=103\)
\(\Rightarrow3\left(29-x\right)=51\)
\(\Rightarrow29-x=17\)
\(\Rightarrow x=12\)
Vậy \(x=12\)
c) \(\left|x-1\right|=4\)
\(\Rightarrow\left[{}\begin{matrix}x-1=4\\x-1=-4\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=5\\x=-3\end{matrix}\right.\)
Vậy \(x=5\) hoặc \(x=-3\)
d) \(\left(-7\right)-x=-21\)
\(\Rightarrow x=-28\)
Vậy \(x=-28\)
Chúc bạn hok tốt !!! Nguyễn Thanh Hằng
a)x=25-12
x=13
b)8.(x-6)=52-12
8.(x-6)=40
x-6=40/8=5
x=5+6
x=11
d)2x-26=22
2x=22+26
2x=30
x=30/2
x=15
c)3x=34+1
\(\Rightarrow\)x=4+1=5
e)x.23=100-91
x.23=9
x=9/8
Bai 4:Theo bai ra ta co:x=4y+3 ;x+y=103
Thay x=4y+3 vao x+y=103 ,ta duoc:
4y+3+y=103
5y+3=103
5y=100
y=100:5=20
Suy ra x=103-20=83
| 2x - 3 | + 4 x 52 = 103
| 2x - 3 | + 100 = 103
| 2x - 3 | =3
=> 2x-3 = |3|
=>2x-3= -3 hay 2x-3 = 3
=>x=0 hay x=3
Vậy x thuộc {0; 3}
| 2x - 3 | + 4 x 52 = 103
| 2x - 3 | + 100 = 103
| 2x - 3 | =3
=> 2x-3 = |3|
=>2x-3= -3 hay 2x-3 = 3
=>x=0 hay x=3
Vậy x thuộc {0; 3}