Tìm x thuộc Z:
a) [(6x - 39) : 7] . 4 = 12
b) (x : 3 - 4) . 5 = 15
c) |x - 5| = |7|
a) x-7=-5
b) 128-3.(x+4)=23
c) [(6x - 39) : 7].4=12
d (x:3-4).5=15
Bài làm
a) x - 7 = 5 b) 128 - 3 . ( x + 4 ) = 23
x = 5 + 7 3 . ( x + 4 ) = 128 - 23
x = 12 3 . ( x + 4 ) = 105
Vậy x = 12 x + 4 = 105 : 3
x + 4 = 35
x = 35 - 4
x = 31
Vậy x = 31
c) [ ( 6x - 39 ) : 7 ] . 4 = 12 d) ( x : 3 - 4 ) . 5 = 15
( 6x - 39 ) : 7 = 12 : 4 x : 3 - 4 = 3 ( chỗ này là làm tắt của x : 3 - 4 = 15 : 5 )
( 6x - 39 ) : 7 = 3 x : 3 = 3 + 4
6x - 39 = 3 . 7 x : 3 = 7
6x - 39 = 21 x = 7 . 3
6x = 21 + 39 x = 21
6x = 60 Vậy x = 21
x = 60 : 6
x = 10
Vậy x = 10
# Chúc bạn học tốt #
x - 7 = -5
x = -5 + 7
x = 2
Vậy x = 2
128 - 3.( x + 4 ) = 23
3.( x + 4 ) = 128 - 23
3.( x + 4 ) = 105
x + 4 = 105 : 3
x + 4 = 35
x = 35 - 4
x = 31
Vậy x = 31
[ ( 6x - 39 ) : 7 ] . 4 = 12
[ ( 6x - 39 ) : 7 ] = 12 : 4
[ ( 6x - 39 ) : 7 ] = 3
( 6x - 39 ) : 7 = 3
6x - 39 = 3 x 7
6x - 39 = 21
6x = 21 + 39
6x = 60
x = 10
Vậy x = 10
( x : 3 - 4 ) . 5 = 15
x : 3 - 4 = 15 : 5
x : 3 - 4 = 3
x : 3 = 3 + 4
x : 3 = 7
x = 21
Vậy x = 21
tìm x
a) x -7 = - 5
b) 128 - 3 . ( x + 4 ) = 23
c) [ ( 6x - 39 ) : 7 ] . 4 = 12
d) ( x : 3 - 4 ) . 5 = 15
cac ban oi giai giup minh nhe cam on
a) x - 7 = -5
=> x = -5 + 7
=> x = 2
b) 128 - 3 . (x + 4) = 23
=> 3.( x + 4) = 128 - 23
=> 3.( x + 4) = 105
=> x + 4 = 105 : 3
=> x + 4 = 35
=> x = 35 - 4
=> x = 31
c) [ ( 6x - 39 ) : 7 ].4 = 12
( 6x -39) : 7 = 12 :4
=> ( 6x - 39 ): 7 = 3
=> 6x - 39 = 3 x 7
=> 6x - 39 = 21
=> 6x = 21 + 39
=> 6x = 60
=> x = 60: 6
=> x = 10
d) ( x: 3 - 4) , 5 = 15
=> x: 3 - 4 = 15 : 5
=> x : 3 - 4 = 3
=> x: 3 = 3+4
=> x: 3 = 7
=> x = 7x 3
=> x =21
a) x -7=-5
x=-5 +7
x=2
b)128-3.(x+4)=23
3.(x+4)=128-23
3.(x+4)=105
x+4=105:3
x+4=35
x=35-4
x=31
c)[(6x-39):7].4=12
(6x-39):7=12:4
(6x-39):7=3
6x-39 =3.7
6x-39 =21
6x =21+39
6x =60
x =60:6
x =10
d)(x:3-4).5=15
x:3-4. =15:5
x:3-4 =3
x:3 =3+4
x:3 =7
x =7.3
x =21
Ai thấy đúng k mk nha
tìm x thuộc Z
a) 1/3 + (-2)/5 + 1/6 + (-1)/5 < x < ( -3)/4 + 2/7 + (-1)/4 + 3/5 + 5/7
b) 5/17 + (-4)/9 + (-20)/31 + 12/17 + (-11)/31 < x/9 < (-3)/7 + 7/15 + 4/(-7) + 8/15 +2/3
Bài 1 : tìm x
a. 128 - 3 . ( x+4 ) =23
b. [( 6x-39 ) : 7 ] . 4 = 12
c. ( x:3 - 4 ) . 5 = 15
d. | x+2 | =0
e. | x-5 | = |-7|
a, 128 - 3.( x + 4 ) = 23 b, [( 6x - 39 ) : 7 ] . 4 = 12 c, ( x : 3 - 4 ) . 5 = 15
3. ( x + 4 ) = 128 - 23 [(6x - 39 ) : 7 ] = 3 ( x : 3 - 4 ) = 3
3. ( x + 4 ) = 105 ( 6x - 39 ) = 21 x : 3 = 7
x + 4 = 35 6x = 21 + 39 x = 7 . 3
x = 35 - 4 6x = 60 x = 21
x = 31 x = 10 Vậy x = 21
Vậy x = 31 Vậy x = 10
Trl:
a. 128 - 3 . ( x + 4 ) = 23
=> 3 . ( x + 4 ) = 128 - 23
=> 3 . ( x + 4 ) = 105
=> x + 4 = 105 : 3
=> x + 4 = 35
=> x = 35 - 4
=> x = 31
Vậy x = 31
b. [( 6x - 39 ) : 7 ] . 4 = 12
=> [( 6x - 39 ) : 7 ] = 12 : 4
=> [( 6x - 39 ) : 7 ] = 3
=> ( 6x - 39 ) = 3 . 7
=> ( 6x - 39 ) = 21
=> 6x = 21 + 39
=> 6x = 60
=> x = 60 : 6
=> x = 10
Vậy x = 10
c. ( x : 3 - 4 ) . 5 = 15
=> ( x : 3 - 4 ) = 15 : 5
=> ( x :3 - 4 ) = 3
=> x : 3 = 3 + 4
=> x : 3 = 7
=> x = 7 . 3
=> x = 21
Vậy x = 21
d. | x + 2 | = 0
=> x + 2 = 0
=> x = 0 - 2
=> x = -2
Vậy x = -2
e. | x - 5 | = |-7|
=> | x - 5 | = 7
=> x - 5 = 7 hoặc x - 5 = -7
=> x = 7 + 5 hoặc x = -7 + 5
=> x = 12 hoặc x = -2
Vậy \(x\in\left\{12;-2\right\}\)
d, | x + 2 | = 0 e, | x - 5 | = | - 7 |
=> x + 2 = 0 | x - 5 | = 7
x = - 2 \(\orbr{\begin{cases}x-5=7\\x-5=-7\end{cases}}\)\(\Leftrightarrow\orbr{\begin{cases}x=12\\x=-2\end{cases}}\)
Vậy x = - 2 Vậy x = 12 hoặc x = - 2
1.tìm x
a)(x=1/4-1/3):(2+1/6-1/4)=7/40
b)13/15-(13/21+x).7/12=7/10
c)(-5/3)^3<x<-24/35.-5/6(x thuộc Z)
tìm x thuộc z ,biết
a,2.(x-5)-3.(x+7)=14
b,5.(x-6)-2.(x+3)=12
c,-5.(2-x)+4.(x-3)=10.x-15
d,-7.(3x-5)+2.(7.x-14)=28
e,5.(4-x)-7.(-x+2)=4-9+3
f,-4.(2.x+1)+8.(3-2.x)=24
\(a,2.\left(x-5\right)-3.\left(x+7\right)=14\)
\(2x-10-3x-21=14\)
\(-x-31=14\)
\(x=-31-14\)
\(x=-45\)
\(b,5.\left(x-6\right)-2\left(x+3\right)=12\)
\(5x-30-2x-6=12\)
\(3x-36=12\)
\(3x=12+36\)
\(3x=48\)
\(x=16\)
\(c,-5.\left(2-x\right)+4.\left(x-3\right)=10.x-15\)
\(-10+5x+4x-12=10x-15\)
\(-6x-22=10x-15\)
\(-6x-10x=-15+22\)
\(-16x=7\)
\(x=-\frac{7}{16}\)
Câu d , e f tương tự nha
Bài : Tìm x thuộc Z , biết :
a) 15 - 5. | x+4 | =-12 - 3
b) ( 4x - 8) . ( 7-x ) = 0
c) ( x^2 - 36) x ( x^2 + 5 ) =0
d) -3. ( x+7) -11 = 2.(x +5)
a) \(15-5\left|x+4\right|=-12-3\)
\(\Leftrightarrow5\left|x+4\right|=30\)
\(\Leftrightarrow\left|x+4\right|=6\)
\(\Leftrightarrow\orbr{\begin{cases}x+4=6\\x+4=-6\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=2\\x=-10\end{cases}}\)
b) \(\left(4x-8\right)\left(7-x\right)=0\Leftrightarrow\orbr{\begin{cases}4x-8=0\\7-x=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=2\\x=7\end{cases}}\)
c) \(\left(x^2-36\right)\left(x^2+5\right)=0\Rightarrow\left(x-6\right)\left(x+6\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-6=0\\x+6=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=6\\x=-6\end{cases}}\)
d) \(-3\left(x+7\right)-11=2\left(x+5\right)\)
\(\Leftrightarrow-3x-32=2x+10\)
\(\Leftrightarrow5x=-42\Rightarrow x=-\frac{42}{5}\)
tìm x,y thuộc Z biết:
a) 12/16=-x/4=21/y=Z/-80
b)5/12=x/-72
c)x+3/15=-1/3
d)3+x/7+y=3/7 và x+y=20
a: \(\Leftrightarrow\dfrac{x}{-4}=\dfrac{21}{y}=\dfrac{z}{-80}=\dfrac{3}{4}\)
=>x=-3; y=28; z=-60
b: 5/12=x/-72
=>x=-72*5/12=-6*5=-30
c: =>x+3=-5
=>x=-8
tìm x, biết :
[ (6x - 39 ) : 7 ] . 4 = 12
( x : 3 - 4 ). 5 = 15
x - [ 42 + ( -28 ) ] = -8
[ ( 6x - 39 ) : 7 ] . 4 = 12
=> ( 6x - 39 ) : 7 = 12 : 4
=> ( 6x - 39 ) : 7 = 3
=> 6x - 39 = 3.7
=> 6x - 39 = 21
=> 6x = 21+39
=> 6x = 60
=> x = 10.
( x : 3 - 4 ) . 5 = 15
=> x : 3 - 4 = 15 : 5
=> x : 3 - 4 = 3
=> x : 3 = 7
=> x = 7.3
=> x = 21
x - [ 42 + (-28) ] = -8
=> x - 14 = -8
=> x = -8 + 14
=> x = 6.
[ (6x - 39): 7] . 4=12
(6x-39) : 7=12:4
(6x -39) :7=3
(6x-39) =3 . 7
6x-39 =21
6x =21 +39
6x=20
x=10
(x :3 -4) .5 =15
(x : 3 -4) =15:5
x:3-4 =3
x : 3=3+4
x:3 =7
x=7 . 3
x=21