( X + 5) - 15 . 13 = 15
6. ( 28 -8 . X ) =72
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
a) 3/13 + 7/12 - 10/13 + 5/12 | d) -5/10 + 12/28 - 3/27 - 7/18 + 20/35 |
b) 15/24 - 6/26 + 28/48 - 30/39 + 10/24 | e) 1/56 + 1/72 + 1/90 + 1/110 + 1/132+ 1/156 = |
c) -1/2 + 3/7 - 1/9 - 7/18 + 4/7 = |
Bài 3
Câu 2) 72 : (x – 15) = 8
Câu 3) 3/ 90 – 3x = 3
Câu 4) 9x - 26= 109
Câu 5) -5x + 13= 23
Câu 6) 3x - 28= -22
Câu 7) 2x : ( -3) = 6
Câu 8) 108 : ( 5 - x ) = -3
Mấy bạn ghi cách viết ra luôn cho mình với
+ \(72:\left(x-15\right)=8\)
\(x-15=9\)
\(x=24\)
+ \(\dfrac{3}{90}-3x=3\)
\(3\left(\dfrac{1}{90}-x\right)=3\)
\(\dfrac{1}{90}-x=1\)
\(x=\dfrac{1}{90}-1=\dfrac{-89}{90}\)
Bài 1: Tính một cách hợp lí:
1) 2155 - ( 174 + 2155 ) + ( -68 + 174 ) 7) -1911 - ( 1234 - 1911 )
2) -25 . 72 + 25 . 21 - 49 . 25 8) 156 . 72 + 28 . 156
3) 35 . ( 14 - 23 ) - 23 . ( 14 - 35 ) 9) 32. ( -39 ) + 16 . ( -22 )
4) 8154 - ( 674 + 8154 ) + ( -98 + 674 ) 10) -1945 - ( 567 - 1945 )
5) -25 . 21 + 25 . 72 + 49 . 25 11) 184 . 33 + 67 . 184
6) 27 . ( 13 - 16 ) - 16 . ( 13 - 27) 12) 44 . ( -36 ) + 22 . ( -28 )
1) 2155-(174+2155)+(-68+174-7)-1911-(1234-1911)
=2155-174-2155+(-68)+174-7-1911-1234+1911
=(2155-2155)+(174-174)+(1911-1911)-(68+7+1234)
= 0 + 0 + 0 - 1309
= -1309
tìm x
a, 280 : ( 7 + 3 : x ) = 4
b, ( x + 5 ) * 19 : 13 = 57
c, 6 * ( 28 - 8 * x ) = 72
a,280: (7 + 3 : x ) = 4
(7 + 3 : x ) = 280:4
( 7+ 3: x) =70
3 : x = 70-7
3:x=63
x=63.3
x= 189
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,6.(28-8.x)=72
(28-8.x)=72:6
(28-8.x)=12
8x=28-12
8x=16
x=16:8
X=2
tìm x
x+5/7=7/8:1/6
15/6-x=5/8×2/15
rút gọn
72/104
điền số tự nhiên thích hợp vào chỗ có dấu chấm
3/13<..../13<......../13<......../13<....../13<......./13<72/104
\(x+\frac{5}{7}=\frac{7}{8}:\frac{1}{6}\)
\(\Leftrightarrow x+\frac{5}{7}=\frac{21}{4}\)
\(\Leftrightarrow x=\frac{127}{28}\)
\(\frac{72}{104}=\frac{72:8}{104:8}=\frac{9}{13}\)
\(\frac{3}{13}< \frac{4}{13}< \frac{5}{13}< \frac{6}{13}< \frac{7}{13}< \frac{8}{13}< \frac{72}{104}=\frac{9}{13}\)
Tìm x :
a ) \(x+\frac{5}{7}=\frac{7}{8}\div\frac{1}{6}=\frac{7\times6}{8\times1}=\frac{21}{4}\)
\(x=\frac{21}{4}-\frac{5}{7}=\frac{127}{28}\)
b ) \(\frac{15}{6}-x=\frac{5}{8}\times\frac{2}{15}=\frac{1}{12}\)
\(x=\frac{15}{6}-\frac{1}{12}=\frac{29}{12}\)
Rút gọn : \(\frac{72}{104}=\frac{72\div8}{104\div8}=\frac{9}{13}\)
Điền STN thích hợp :
\(\frac{3}{13}< \frac{4}{13}< \frac{5}{13}< \frac{6}{13}< \frac{7}{13}< \frac{8}{13}< \frac{9}{13}\left(\frac{72}{104}\right)\)Những số cần điền là : 4, 5, 6, 7, 8 .
==========> CHÚC HỌC GIỎI NHỚ K MÌNH <==========
Tính hợp lí nhất:
1) 2155 - (174 + 2155) + (-68 + 174)
2) -25 . 72 + 25 . 21 - 49 . 25
3) 35(14 - 23) - 23(14 - 35)
4) 8154 - (674 + 8154) + (-98 + 674)
5) -25 . 21 + 25 . 72 + 49 . 25
6) 27(13 - 16) - 16(13 - 27)
7) -1911 - (1234 - 1911)
8) 156 . 72 + 28 . 156
9) 32 . (-39) + 16.(-22)
10) -1945 - ( 567 - 1945)
11) 184 . 33 + 67 . 184
12) 44 . (-36) + 22 . (-28)
( Mk cần gấp)
1) 2155-(174+2155)+(-68+174)
=2155-174-2155-68+174
=2155-2155+174-174-68
=0+0-68
=-68
2) -25.72+25.21-49.25
=25.[(-72)+21-49]
=25.(-100)
=-2500
3) 35(14 - 23) - 23(14 - 35)
= 35.14 - 35.23 - (23.14 - 23.35)
= 35.14 - 35.23 - 23.14 + 23.35
= (35.14 - 23.14) + (23.55 - 35.23)
= 14.(35-23) + 0
= 14.12 + 0
= 168
4) 8154 - (674 + 8154) + (-98 + 674)
= 8154 - 674 - 8154 - 98 + 674
= (8154 - 8154) + (674 - 674) - 98
= 0 + 0 - 98
= -98
5) (-25).21 + 25.72 + 49.25
= 25.[(-21) + 72 + 49]
= 25.100
= 2500
6) 27(13 - 16) - 16(13 - 27)
= 27.13 - 27.16 - (16.13 - 16.27)
= 27.13 - 27.16 - 16.13 + 16.27
= (27.13 - 16.13) + (16.27 - 27.16)
= 13.(27-16) + 0
= 13.11 + 0
= 143
7) (-1911) - (1234 - 1911)
= (-1911) - 1234 + 1911
= [(-1911) + 1911] - 1234
= 0 - 1234
= -1234
8) 156.72 + 28.156
= 156.(72+28)
= 156.100
= 15600
9) 32.(-39) + 16.(-22)
= 16.2.(-39) + 16.(-22)
= 16.(-78) + 16.(-22)
= 16.[(-78) + (-22)]
= 16.(-100)
= -1600
10) (-1945) - (567 - 1945)
= (-1945) - 567 + 1945
= [(-1945) + 1945] - 567
= 0 - 567
= -567
11) 184.33 + 67.184
= 184.(33 + 67)
= 184.100
= 18400
12) 44.(-36) + 22.(-28)
= 22.2.(-36) + 22.(-28)
= 22.(-72) + 22.(-28)
= 22.[(-72) + (-28)]
= 22.(-100)
= -2200
Tính theo mẫu :
Mẫu : 13/21 + 5/7 = 13/21 + 5 x 3 / 7 x 3 = 13/21 + 15/21 = 28/21
26/81 + 4/27
5/64 + 7/8
\(\dfrac{26}{81}+\dfrac{4}{27}=\dfrac{26+12}{81}=\dfrac{38}{81}\)
\(\dfrac{5}{64}+\dfrac{7}{8}=\dfrac{5+56}{64}=\dfrac{61}{64}\)
\(\dfrac{26}{81}+\dfrac{4}{27}=\dfrac{26}{81}+\dfrac{4\times3}{27\times3}=\dfrac{26}{81}+\dfrac{12}{81}=\dfrac{38}{81}\)
\(\dfrac{5}{64}+\dfrac{7}{8}=\dfrac{5}{64}+\dfrac{7\times8}{8\times8}=\dfrac{5}{64}+\dfrac{56}{64}=\dfrac{61}{64}\)
a)15×17-15/15×16+10
b)23×29-10/23×28+13
c)75×8+25/75×82-50
d)53+153×156/153×157-100
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