- Tìm x : 73.x-2-2.72=72.5
- Nếu làm đúng mình sẽ tick 10 lan một ngày
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Ta có :
\(\frac{x-3}{97}+\frac{x-27}{73}+\frac{x-67}{33}+\frac{x-73}{27}=4\)
\(\Leftrightarrow\left(\frac{x-3}{97}-1\right)+\left(\frac{x-27}{73}-1\right)+\left(\frac{x-67}{33}-1\right)+\left(\frac{x-73}{27}-1\right)=0\)
\(\Leftrightarrow\frac{x-100}{97}+\frac{x-100}{73}+\frac{x-100}{33}+\frac{x-100}{27}=0\)
\(\Leftrightarrow\left(x-100\right)\left(\frac{1}{97}+\frac{1}{73}+\frac{1}{33}+\frac{1}{27}\right)=0\)
Vì \(\frac{1}{97}+\frac{1}{73}+\frac{1}{33}+\frac{1}{27}>0\) Nên \(x-100=0\)
\(\Leftrightarrow x=100\)
Vậy \(x=100\)
\(\Leftrightarrow\frac{x-3}{87}+\frac{x-27}{79}+\frac{x-67}{33}+\frac{x-73}{27}-4=0\)
\(\Leftrightarrow\left(\frac{x-3}{97}-1\right)+\left(\frac{x-27}{73}-1\right)+\left(\frac{x-67}{33}-1\right)+\left(\frac{x-73}{27}-1\right)=0\)
\(\Leftrightarrow\left(\frac{x-3-97}{97}\right)+\left(\frac{x-27-73}{73}\right)+\left(\frac{x-67-33}{33}\right)+\left(\frac{x-73-27}{27}\right)=0\)
\(\Leftrightarrow\frac{x-100}{97}+\frac{x-100}{73}+\frac{x-100}{33}+\frac{x-100}{27}=0\)
\(\Leftrightarrow\left(x-100\right)\left(\frac{1}{97}+\frac{1}{73}+\frac{1}{33}+\frac{1}{27}\right)=0\)
Vì \(\frac{1}{97}+\frac{1}{73}+\frac{1}{33}+\frac{1}{27}\ne0\)
\(\Rightarrow x-100=0\Leftrightarrow x=100\)
\(a,\)\(9-25=\left(7-x\right)-\left(25+7\right)\)
\(-16=\left(7-x\right)-32\)
\(7-x=-16+32\)
\(7-x=16\)
\(x=7-16=-9\)
\(b,-7624+\left(1543+7624\right)-x=25\)
\(-7624+9167-x=25\)
\(1543-x=25\)
\(x=1543-25\)
\(x=1518\)
\(c,\left(27-514\right)-\left(486-73\right)+x=7\)
\(-487-413+x=7\)
\(-900+x=7\)
\(x=7+900\)
\(x=907\)
\(\left(x+1\right)\left(y-2\right)=3\)
\(\Rightarrow\left(x-1\right),\left(y-2\right)\inƯ\left(3\right)=\left\{\pm1;\pm2\right\}\)
\(TH1:\hept{\begin{cases}x+1=1\\y-2=3\end{cases}\Rightarrow\hept{\begin{cases}x=0\\y=5\end{cases}}}\) \(TH2:\hept{\begin{cases}x+1=-1\\y-2=-3\end{cases}\Rightarrow\hept{\begin{cases}x=-2\\y=-1\end{cases}}}\)
\(TH3:\hept{\begin{cases}x+1=3\\y-2=1\end{cases}\Rightarrow\hept{\begin{cases}x=2\\y=3\end{cases}}}\) \(TH4:\hept{\begin{cases}x+1=-3\\y-2=-1\end{cases}\Rightarrow\hept{\begin{cases}x=-4\\y=1\end{cases}}}\)
Vậy ............................
b, Làm tương tự
\(y\times28+y\times73-y=3200\\\Rightarrow y\times\left(28+73-1\right)=3200\\ \Rightarrow y\times100=3200\\ \Rightarrow y=3200:100\\ \Rightarrow y=32\)
Bổ sung bài : Tính nhanh
\(46.57-38.73+57.54-73.62\)
\(=\left(46.57+57.54\right)-\left(38.73+73.62\right)\)
\(=57\left(46+54\right)-73\left(38+62\right)\)
\(=57.100-73.100\)
\(=5700-7300=-1600\)
46 x 57 -38x73+57x54-73x62
=57x(46+54)-73x(38+62)
=57x100-73x100
=100(57-73)
=100x (-16)
=-1600
Bài 1
3x+10 chia hết cho x+1
Ta có
3x+10 =x+x+x+1+1+1+7=(x+1)+(x+1)+(x+1)+7
Ta thấy (x+1)+(x+1)+(x+1)chia hết cho x+1
suy ra 7 chia hết cho x+1 , suy ra x+1 là ước của 7 =(1,7)
Ta có
x+1=1 suy ra x=0
x+1=7 suy ra x=6
Vậy x bằng 0 và 6
73.x-2 - 2 . 72 = 72 x 5
73.x-2 - 2 . 49 = 49 x 5
73.x-2 - 98 = 245
73.x-2 = 245 + 98
73.x-2 = 343
73.x-2 = 73
3.x - 2 = 3
3.x = 5
x = 5 : 3
x = 5/3
73x-2 =72.5 +2.72 =73
3x-2 = 3
x = 5/3
xem có giu loi hua k ?