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Câu 2:
\(\dfrac{7}{9}\cdot\dfrac{3}{35}=\dfrac{1}{5}\cdot\dfrac{1}{3}=\dfrac{1}{15}\)
\(\dfrac{9}{22}\cdot55=\dfrac{9\cdot55}{22}=\dfrac{9\cdot5}{2}=\dfrac{45}{2}\)
a) X x 48 + 52 x X =160
X x ( 48+52) = 160
X x 100 = 160
X = 8/5
b) 7 x ( 8+2xX) =210
8+2xX = 30
2xX= 22
X= 11
c) X x 56 + 44 x X+285 x X =130
X x ( 56+44+285)= 130
X x 385 =130
X = 26/77
d) (x-12) x 17 : 11= 51
( x-12) x17 =561
x-12 = 33
x= 45
e) 915 x X +285 x X =48
X x( 915+285) = 48
X x 1200 = 48
X =1/25
\(48x+52x=160\)
\(x.\left(48+52\right)=160\)
\(100x=160\)
\(x=\frac{160}{100}\)
\(x=1,6\)
Vậy \(x=1,6\)
Đăng ít thôi b
\(1)\)
\(-3-18\)
\(=-(3+18)\)
\(=-21\)
\(-7\times-5\)
\(=7\times(-1)\times(-5)\)
\(=7\times5\)
\(=35\)
\(5+(-11)\)
\(=5-11\)
\(=-6\)
1,
a) -3 - 18=-21
b) (-7).(-5)=35
c) 5+(-11)=-6
2,
a) -2-13+(-14)-19=-48
b) 221 + 4[(-5).8-4]=45
c) (-2)3.(-2)2+32=0
d) -15.12 - 8.(-12)=-84
3,
a) x:(-2)=9
=>x =9.(-2)
=>x =-18
b)4x+(-8)=24
=>4x =24-(-8)
=>4x =32
=>x =32:4
=>x =8
c) (3x)(x+7)=0
\(\Rightarrow\hept{\begin{cases}3x=0\\x+7=0\end{cases}\Rightarrow\hept{\begin{cases}x=0:3\\x=0-7\end{cases}\Rightarrow}\hept{\begin{cases}x=0\\x=-7\end{cases}}}\)
\(3x+12=36\)
\(\Leftrightarrow3x=36-12\)
\(\Leftrightarrow3x=24\)
\(\Leftrightarrow x=24\div3\)
\(\Leftrightarrow x=8\)
\(4x+28=134\)
\(\Leftrightarrow4x=134-28\)
\(\Leftrightarrow4x=106\)
\(\Leftrightarrow x=106\div4\)
\(\Leftrightarrow x=\frac{53}{2}\)
\(5x-22=-17\)
\(\Leftrightarrow5x=22-17\)
\(\Leftrightarrow5x=5\)
\(\Leftrightarrow x=5\div5\)
\(\Leftrightarrow x=1\)
3x + 12 = 36
3x = 36 - 12
3x = 24
x = 8
4x + 28 = 134
4x = 134 - 28
4x = 106
x = 106 : 4
x = 26 , 5
5x - 22 = -17
5x = -17 + 22
5x = 5
x = 1
3x - 184 = -49
3x = -49 + 184
3x = 135
x = 135 : 3 = 45
4x + 12 = 56
4x = 56 - 12
4x = 44
x = 11
3x - 127 = - 22
3x = -22 + 127
3x = 105
x = 105 : 3 = 35
3x + 22 = 124
3x = 124 - 22 = 102
x = 102 : 3
x = 34
4x - 9 = 31
4x = 31 + 9 = 40
x = 40 : 4= 10
5x - 211 = -31
5x = -31 + 211
5x = 180
x = 180 : 5
x = 36
a) (x-12)*17:11=51
(x-12)=51:(17:11)
x-12=33
x=33+12
x=45
b) 4*(36-4*x)=64
(36-4*x)=64:4
(36-4*x)=16
x=16:(36-4)
x=0.5
c) (x+5)*19:13=57
(x+5)=57:(19:13)
x+5=39
x=39-5
x=34
a) 4 × (5 - x) = x
20 - 4x = x
x + 4x = 20
5x = 20
x = 20 : 5
x = 4
b) 1/2 (x - 14) = 2
x - 14 = 2 : 1/2
x - 14 = 4
x = 4 +14
x = 18
c) 18/13 + 3 × x = 3
3x = 3 - 18/13
3x = 21/13
x = 21/13 : 3
x = 7/13
d) đề khó hiểu
a) 245 - x = 27 b) 3x + 41 = 56 c) 238: 2x = 17 d) 3x - 90 = 24 e) 2x:5 = 124 h) 26 + 3x = 25 + 46
x = 245 - 27 3x = 56 -41 2x = 238: 17 3x = 24 + 90 2x = 124.5 6 + 3x = 71
x = 218 3x = 15 2x = 14 3x = 114 2x = 620 3x = 71 - 6
x = 15 : 3 x = 14: 2 x = 114: 3 x = 620:2 3x = 65
x = 5 x = 7 x = 38 x = 310 x = 65: 3
x = 21,66
\(a,245-x=27\)
\(x=245-27\)
\(x=218\)
\(b,3x+41=56\)
\(3x=56-41\)
\(3x=15\)
\(x=15:3\)
\(x=5\)
\(c,238:2x=17\)
\(2x=238:17\)
\(2x=14\)
\(x=14:2\)
\(x=7\)
\(d,3x-90=24\)
\(3x=24+90\)
\(3x=114\)
\(x=114:3\)
\(x=38\)
\(e,2x:5=124\)
\(2x=124\times5\)
\(2x=620\)
\(x=620:2\)
\(x=310\)
\(f,7x+4x=110\)
\(\left(7+4\right)x=110\)
\(11x=110\)
\(x=110:11\)
\(x=10\)
\(g,5x-x=444\)
\(\left(5-1\right)x=444\)
\(4x=444\)
\(x=444:4\)
\(x=111\)
\(h,26+3x=25+46\)
\(26+3x=71\)
\(3x=71-26\)
\(3x=45\)
\(x=45:3\)
\(x=15\)
Học tốt
1.Tính :
\(\frac{12}{17}\):6=\(\frac{2}{17}\); 16:\(\frac{8}{11}\)=\(\frac{2}{11}\); 9:\(\frac{3}{5}\)x\(\frac{4}{15}\)=\(\frac{3}{5}\)x\(\frac{4}{15}\)=\(\frac{4}{25}\)
=12/17×1/6
=2/17
=16/1×11/8
=22
9/1×5/3×4/15
15/1×4/15
4/1
#)Giải :
\(\frac{17}{15}+x=\frac{5}{11}+\frac{17}{11}\)
\(\frac{17}{15}+x=2\)
\(\Rightarrow x=\frac{13}{15}\)