-9/12=30/x=y/20=7/-44
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19 tháng 11 2021
noooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
TG
2 tháng 8 2020
1) \(373737.73-37.737373\)
\(=37.10101.73-37.73.10101\)
\(=0\)
2) \(19.41414141-41.19191919\)
\(=19.41.1010101-41.19.1010101\)
\(=0\)
3) \(123456.456789456789-456789.123456123456\)
\(=123456.456789.1000001-456789.123456.1000001\)
\(=0\)
4) \(250.12.7\)
\(=250.4.3.7\)
\(=\left(250.4\right).\left(3.7\right)\)
\(=1000.21\)
\(=21000\)
5) \(24.125.9\)
\(=3.8.125.9\)
\(=\left(3.9\right).\left(8.125\right)\)
\(=27.1000\)
\(=27000\)
6) \(125.44.18\)
\(=125.4.11.2.9\)
\(=\left(125.4.2\right).\left(11.9\right)\)
\(=1000.99\)
\(=99000\)
7) \(8.24.6+12.4.52+2.22.24\)
\(=48.24+48.52+48.22\)
\(=48\left(24+52+22\right)\)
\(=48.98\)
\(=48\left(100-2\right)\)
\(=48.100-48.2\)
\(=4800-96\)
\(=4704\)
8) \(18.58.2-9.27.4+12.69.3\)
\(=36.58-36.27+36.69\)
\(=36\left(58-27+69\right)\)
\(=36.100=3600\)
9) \(30.85.3+18.72.5-45.37.2-9.20.10\)
\(=90.85+90.72-90.37-90.20\)
\(=90\left(85+72-37-20\right)\)
\(=90.100=9000\)
Y
9 tháng 3 2023
\(\dfrac{7}{16}+\dfrac{-1}{8}+\dfrac{9}{32}=\dfrac{14}{32}-\dfrac{4}{32}+\dfrac{9}{32}=\dfrac{19}{32}\)
\(\dfrac{5}{4}-\dfrac{25}{30}\times\dfrac{37}{44}+\dfrac{-25}{30}\times\dfrac{13}{44}+\dfrac{-25}{30}\times\dfrac{-6}{44}\)
\(=-\dfrac{25}{30}\times\left(\dfrac{5}{4}+\dfrac{37}{44}+\dfrac{13}{44}-\dfrac{6}{44}\right)\)
\(=-\dfrac{25}{30}\times\left(\dfrac{55}{44}+\dfrac{37}{44}+\dfrac{13}{44}-\dfrac{6}{44}\right)\)
\(=-\dfrac{25}{30}\times\dfrac{99}{44}\)
\(=-\dfrac{5}{6}\times\dfrac{9}{4}\)
\(=-\dfrac{15}{8}\)
H9
HT.Phong (9A5)
CTVHS
9 tháng 3 2023
\(\left(\dfrac{7}{16}+\dfrac{-1}{8}+\dfrac{9}{32}\right):\dfrac{5}{4}\)
\(=\left(\dfrac{14}{32}+\dfrac{-4}{32}+\dfrac{9}{32}\right):\dfrac{5}{4}\)
\(=\dfrac{19}{32}:\dfrac{5}{4}\)
\(=\dfrac{19}{32}.\dfrac{4}{5}=\dfrac{19.4}{32.5}=\dfrac{19}{40}\)
\(\dfrac{-25}{30}.\dfrac{37}{44}+\dfrac{-25}{30}.\dfrac{13}{44}+\dfrac{-25}{30}.\dfrac{-6}{44}\)
\(=\dfrac{-25}{30}.\left(\dfrac{37}{44}+\dfrac{13}{44}+\dfrac{-6}{44}\right)\)
\(=\dfrac{-25}{30}.\dfrac{44}{44}=\dfrac{-5}{6}.1=-\dfrac{5}{6}\)
10 tháng 7 2023
1: =-2/9(15/17+2/17)=-2/9
2: \(=\dfrac{-6}{3}+\dfrac{-21}{90}\)
=-2-7/30=-67/30
3: \(=\dfrac{3}{4}\cdot\dfrac{7}{5}+\dfrac{9}{7}\cdot\dfrac{3}{2}\)
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
10 tháng 7 2023
1: =-2/9(15/17+2/17)=-2/9
2: =−63+−2190=−63+−2190
=-2-7/30=-67/30
3: =34⋅75+97⋅32=34⋅75+97⋅32
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
H9
HT.Phong (9A5)
CTVHS
13 tháng 11 2023
a) Ta có: \(\dfrac{x}{y}=\dfrac{20}{9}\Rightarrow\dfrac{x}{20}=\dfrac{y}{9}\)
Áp dụng tính chất dãy tỉ số bằng nhau ta có:
\(\dfrac{x}{20}=\dfrac{y}{9}=\dfrac{x-y}{20-9}=\dfrac{-44}{11}=-4\)
\(\Rightarrow\left\{{}\begin{matrix}x=20\cdot-4=-80\\y=-4\cdot9=-36\end{matrix}\right.\)
b) \(\dfrac{x}{y}=2\dfrac{1}{2}\Rightarrow\dfrac{x}{y}=\dfrac{5}{2}\Rightarrow\dfrac{x}{5}=\dfrac{y}{2}\)
Áp dụng tính chất dãy tỉ số bằng nhau ta có:
\(\dfrac{x}{5}=\dfrac{y}{2}\Rightarrow\dfrac{x+y}{5+2}=\dfrac{40}{7}\)
\(\Rightarrow\left\{{}\begin{matrix}\text{x}=\dfrac{40}{7}\cdot5=\dfrac{200}{7}\\y=\dfrac{40}{7}\cdot2=\dfrac{80}{7}\end{matrix}\right.\)
22 tháng 11 2018
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50=1275
QA
2
23 tháng 6 2015
12 phút 30 giây * 6 = 72 phút 180 giây hay 1 giờ 15 phút
3 giờ 20 phút : 5 = 0 giờ 40 phút
\(\frac{5}{6}:\left(y-\frac{7}{9}\right)=\frac{3}{4}\)
\(\left(y-\frac{7}{9}\right)=\frac{5}{6}:\frac{3}{4}\)
\(y-\frac{7}{9}=\frac{10}{9}\)
\(y=\frac{10}{9}+\frac{7}{9}\)
\(y=\frac{17}{9}\)
23 tháng 6 2015
74 ' 20 giây
40'
5/6 : ( y + 7/9 ) = 3/4
y + 7/9 = 5/6 : 3/4
y + 7/9 = 10/9
y = 10/9 - 7/9
y = 1/3
Mình làm trước nên **** !
15 tháng 1 2018
a, | x - 7 | = | -12 |
TH1: x - 7 =12
=> x = 12 + 7 =19
TH2: x - 7 = -12
=> x = -12 + 7 = -5
Vậy x = 19 hoặc x = -5
b, | 2x - 1 | = -(-9)
=> | 2x - 1 | = 9
TH1: 2x - 1 = 9
=> 2x = 9 + 1 = 10
=> x = 10 : 2 =5
TH2: 2x - 1= - 9
=> 2x = - 9 + 1 = -8
=> x = - 8 : 2 = - 4
Vậy x = 5 hoặc x = -4
c, x- (19-x)=x - 17
=> x - 19 + x = x - 17
=> x + x - x = -17 + 19 [[ khi chuyển vế sẽ như này nhé ! ]]
=> x = 2
Còn câu d để từ từ ........................ :)))))))
21 tháng 6 2022
1: \(=\dfrac{1}{29\cdot30}-\left(\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+...+\dfrac{1}{28\cdot29}\right)\)
\(=\dfrac{1}{29\cdot30}-\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{28}-\dfrac{1}{29}\right)\)
\(=\dfrac{1}{29\cdot30}-\dfrac{28}{29}=\dfrac{1-28\cdot30}{870}=\dfrac{-859}{870}\)