a) 7,2 : 2,4 x X = 4,5
b) ( X x 3 + 4 ) : 5 = 8
c) ( X + 5 ) x 19 : 13 = 57
d) ( x : 2 + 50 ) : 5 = 12
Tính hợp lí ( Giúp mk với )
A = (-4/5 + 4/3) + (-5/4 + 14/5) - 7/3
B = 8/3 x 2/5 x 3/8 x 10 x 19/92
C = -5/7 x 2/11 + (-5)/7 x 9/14 + 1/57
D = 12/19 x 7/15 x (-13)/17 x 19/12 x 17/13
E = 1/1x2 + 1/2x3 + 1/3x4 + ....+ 1/49 x 50
A = ( -4/5 + 4/3 ) + (-5/4 + 14/5) - 7/3
= 8/15 + 31/20 - 7/3
= 25/12 - 7/3
= -1/4
B = 8/3 x 2/5 x 3/8 x 10x 19/92
= 16/15 x 15/4 x 19/92
= 4x19/92
= 19/23
C = - \(\dfrac{5}{7}\) x \(\dfrac{2}{11}\) + \(\dfrac{-5}{7}\) x \(\dfrac{9}{14}\) + \(\dfrac{1}{57}\)
= - \(\dfrac{10}{77}\) - \(\dfrac{45}{98}\) + \(\dfrac{1}{57}\)
= - \(\dfrac{635}{1078}\) + \(\dfrac{1}{57}\)
= - \(\dfrac{36195}{61446}\) + \(\dfrac{1078}{61446}\)
= - \(\dfrac{35117}{61446}\)
D = \(\dfrac{12}{19}\) x \(\dfrac{7}{15}\) x \(\dfrac{-13}{17}\) x \(\dfrac{19}{12}\) x \(\dfrac{17}{13}\)
D = (\(\dfrac{12}{19}\) x \(\dfrac{19}{12}\)) x (- \(\dfrac{13}{17}\) x \(\dfrac{17}{13}\)) x \(\dfrac{7}{15}\)
D = 1 x (- 1) x \(\dfrac{7}{15}\)
D = -1 x \(\dfrac{7}{15}\)
D = - \(\dfrac{7}{15}\)
Tìm x , biết : (x + 5)^2 - (x - 3) (x + 7) = 19 . Kết quả x bằng :
A : -8
B : 8
C : 4
D : -4,5
\(\left(x+5\right)^2-\left(x-3\right)\left(x+7\right)=19\\ x^2+10x+25-\left(x^2+7x-3x-21\right)=19\\ x^2+10x+25-x^2-7x+3x+21=19\\ 6x+46=19\\ 6x=19-46\\ 6x=-27\\ x=\dfrac{-27}{6}\\ x=-4,5\)
Chọn D
Tìm X
a) 7,2 : 2,4 x X = 4,5
b) 9,15 x X + 2,85 x X = 48
c) (X x 3 + 4) : 5 = 8
d) (15 x 28 – X) : 2/5 = 200 : 0,4
e) X x 4,8 + 5,2 x X = 160
g) 7 x (8 + 2 x X) = 210
h) X x 5,6 + 4,4 x X =130
i) (X – 12) x 17 : 11 = 51
k) 9,15 x X + 2,85 x X = 48
Chắc mới lên lớp 6, nên chưa biết thay dấu nhân bằng dấu chấm.
a) ( x . 7 + 8 ) : 5 = 10
b) ( x + 5 ) . 19 : 13 = 57
c) 4 . ( 36 - 4 . x ) = 64
d) 7,6 : 1,9 . x = 3,2
e) ( x : 2 + 50 ) : 5 = 12
g) 280 : ( 17 + 3 . x ) = 4
h ) 6. ( 28 - 8 . x ) = 72
i) ( x - 15 ) : 3 : 12 = 6
giúp mh với nha các bn
a) (x.7 + 8) : 5 = 10
x.7 + 8 = 10.5
x.7 + 8 = 50
x.7 = 50 - 8
x.7 = 42
x = 42 : 7
x = 6
b) (x + 5).19 : 13 = 57
(x + 5).19 = 57 . 13
(x + 5).19 = 741
x + 5 = 741 : 19
x + 5 = 39
x = 39 - 5
x = 34
c) 4.(36 - 4.x) = 64
36 - 4x = 64 : 4
36 - 4x = 16
4x = 36 - 16
4x = 20
x = 20 : 4
x = 5
d) 7,6 : 19 . x = 3,2
0,4 . x = 3,2
x = 3,2 : 0,4
x = 8
e) (x : 2 + 50) : 5 = 12
x : 2 + 50 = 12 . 5
x : 2 + 50 = 60
x : 2 = 60 - 50
x : 2 = 10
x = 10 . 2
x = 20
g) 280 : (17 + 3.x) = 4
17 + 3x = 280 : 4
17 + 3x = 70
3x = 70 - 17
3x = 53
x = 53/3
h) 6.(28 - 8.x) = 72
28 - 8x = 72 : 6
28 - 8x = 12
8x = 28 - 12
8x = 16
x = 16 : 8
x = 2
i) (x - 15) : 3 : 12 = 6
(x - 15) : 3 = 6 . 12
(x - 15) : 3 = 72
x - 15 = 72 . 3
x - 15 = 216
x = 216 + 15
x = 231
bài 2
a) 7,2: 2,4 . x = 45
b) 9,15 . x + 2,85 . x = 48
c) ( x . 3 + 4 ) : 5 = 8
d) ( 15 . 28 - x ) : 2/5 = 200 : 0,4
e) x . 4,8 + 5,2 . x = 160
g) 7. ( 8+ 2 . x ) = 210
h) x . 5,6 + 4,4 . x = 130
i) ( x - 12 ) . 7 : 11 = 51
giúp mh với mh đang cần gấp
Bài 2:
a, 7,2: 2,4.\(x\) = 45
3.\(x\) = 45
\(x\) = 45: 3
\(x\) = 15
b, 9,15.\(x\) + 2,85.\(x\) = 48
\(x\).( 9,15 + 2,85) = 48
12\(x\) = 48
\(x\) = 48: 12
\(x\) = 4
c) (x.3 + 4) : 5 = 8
x.3 + 4 = 8 x 5
x.3 + 4 = 40
x.3 = 40 - 4
x.3 = 36
x = 36 : 3
x = 12
d, (15.28 - \(x\)) : \(\dfrac{2}{5}\) = 200: 0,4
(420 - \(x\)) : \(\dfrac{2}{5}\) = 500
420 - \(x\) = 500 \(\times\) \(\dfrac{2}{5}\)
420 - \(x\) = 200
\(x\) = 420 - 200
\(x\) = 220
a,x - 1/2 - (-1/6)
b,x + 5/6 = 3/8
c,2/3 . x -1/2 = 5/6
d, x/7 = 6/-21
e,(7/3 x -0,6) : 3^2/5 = 1
f,x/45 = 5/6 + -29/30
g,(4,5 - 2x) . (-1^4/7) =11/14
h,-2/7 + 4/7x=5/7
b: \(x+\dfrac{5}{6}=\dfrac{3}{8}\)
=>\(x=\dfrac{3}{8}-\dfrac{5}{6}\)
=>\(x=\dfrac{9}{24}-\dfrac{20}{24}=-\dfrac{11}{24}\)
c: \(\dfrac{2}{3}x-\dfrac{1}{2}=\dfrac{5}{6}\)
=>\(\dfrac{2}{3}x=\dfrac{5}{6}+\dfrac{1}{2}=\dfrac{8}{6}=\dfrac{4}{3}\)
=>2x=4
=>x=4/2=2
d: \(\dfrac{x}{7}=\dfrac{6}{-21}\)
=>\(\dfrac{x}{7}=\dfrac{-2}{7}\)
=>x=-2
e: \(\left(\dfrac{7}{3}x-0,6\right):\dfrac{3^2}{5}=1\)
=>\(\dfrac{7}{3}x-0,6=\dfrac{3^2}{5}=1,8\)
=>\(\dfrac{7}{3}x=2,4\)
=>\(x=2,4:\dfrac{7}{3}=2.4\cdot\dfrac{3}{7}=\dfrac{7.2}{7}=\dfrac{36}{35}\)
f: \(\dfrac{x}{45}=\dfrac{5}{6}+\dfrac{-29}{30}\)
=>\(\dfrac{x}{45}=\dfrac{25}{30}-\dfrac{29}{30}=-\dfrac{4}{30}=-\dfrac{2}{15}\)
=>\(x=-\dfrac{2}{15}\cdot45=-6\)
g: \(\left(4,5-2x\right)\cdot\left(-\dfrac{1^4}{7}\right)=\dfrac{11}{14}\)
=>\(4,5-2x=\dfrac{11}{14}:\dfrac{-1}{7}=\dfrac{-11}{2}\)
=>\(2x=4,5+\dfrac{11}{2}=\dfrac{20}{2}=10\)
=>x=10/2=5
h: \(-\dfrac{2}{7}+\dfrac{4}{7}x=\dfrac{5}{7}\)
=>\(\dfrac{4}{7}x=\dfrac{5}{7}+\dfrac{2}{7}=\dfrac{7}{7}\)
=>4x=7
=>\(x=\dfrac{7}{4}\)
BÀI 1 :TÌM X :
1 ) 17,75 - ( 0,5 * x : 2 - 4,2 ) = 15
2 ) x : 6 * 7,2 + 1,3+ x + x : 2 + 15 = 19,95
3) 7 : ( 3,8 * x - 57/19 + 3 ) = 1,75
4) 7,75 - ( 0,5 * x : 5 - 6,2 ) =5
5) [(x + 47,5 ) * 2,5 - 0,2] : 1,25 = 12,48
6) 49 * ( x : 23 ) = 316
7) (3 + 5 + 7 + ... + 55 + 57 ) * x = 2520
8) 12 * ( x * 2,4 - 0,23 - 0,05 ) = 1,44
Bài 1 tìm x biết
a> x=7/25+-1/5
b> x=5/11+4/-9
c> x/3=2/3+-1/7
d> x/5=5/6+-19/30
e> x/6=3/2+-7/15
Bài 2 cộng các phân số sau
a> -650/1430+588/686
b> 2004/2010+8/-670
Bài 3 tìm x biết
a> -5/13+-4/13 < x/13 < 2/13+-7/13
b> 3/2+-1/3 <x/6 < 1/9+31/18
c> -5/19+3/19 < x/19 bé hơn hoặc bằng 13/19+-11/19
d> -7/8+5/6 bé hơn hoặc bằng x/24 bé hơn hoặc bằng 5/8+-5/12
Bài 1 :
\(a)x=\frac{7}{25}+\left(-\frac{1}{5}\right)\)
\(x=\frac{2}{25}\)
\(b)x=\frac{5}{11}+\left(\frac{4}{-9}\right)\)
\(x=\frac{1}{99}\)
Mấy câu kia dễ tự làm :>
Tìm x, giải chi tiết ra:
1. [(2 x \(x\)+ 50) x 5 - 200] : 10 = 30
2. 36 - (1,5 x 26 : x) = 1,2 x 15 + 70 :5
3. (\(x\)- 140) : 35 = 270
4. 460 + 85 x 4 = (\(x\)+ 200) : 4
5. 7,2 : 2,4 x \(x\)= 4,5
6. 2448 : [119 - (\(x\)- 6)] = 24
7. 156 - (\(x\)+ 61) = 82
8. (2958 + \(x\)) : 134 = 87
9. (5376 - \(x\)) - 3877 = 904
10: 231 - (\(x\) - 6) = 1339 : 13
11. 4 x \(x\)- [(8000 - 3576) - (2031 - 1598)] = 400
12. \(x\)- 4867 = (175 x 2 + 50 x 70) : 25 + 23
13. 420 : (\(x\): 39) = 105
14. \(x\): (1001 : 13) = 29
15. 70 - 5 x (\(x\)- 3) = 45
Sáng mai mình cần nộp! Ai nhanh nhất cho nhiều like!
15) 70 - 5 . ( x - 3 ) = 45
5 . ( x - 3 ) = 70 - 45
5 . ( x - 3 ) = 25
x - 3 = 25 : 5
x - 3 = 5
x = 5 + 3
x = 8
14 ) x : ( 1001 : 13 ) = 29
x : 77 = 29
x = 29 . 77
x = 2233
13 ) 420 : ( x : 39 ) = 105
x : 39 = 420 : 105
x : 39 = 4
x = 4 . 39
x = 156