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(\(\frac45:\frac65\) + \(\frac15\) : \(\frac{1}{x}\)) x 30 - 26 = 54
(\(\frac45\times\frac56\) + \(\frac15\times x\)) x 30 = 54 + 26
(\(\frac23+\frac15x\)) x 30 = 80
\(\frac23+\frac15x\) = 80 : 30
\(\frac23+\frac15x=\frac83\)
\(\frac15x=\frac83-\frac23\)
\(\frac15x\) = 2
\(x=2:\frac15\)
\(x=2\times5\)
\(x=10\)
Vậy \(x=10\)
6,3 x y + 3,7 x y = 100
y x (6,3 + 3,7) = 100
y x 10 = 100
y = 100 : 10
y = 10
Vậy y = 10
\(\dfrac{8}{9}\) : ( 2 - 3 \(\times\) y) = \(\dfrac{5}{3}\)
2 - 3 \(\times\) y = \(\dfrac{8}{9}\) : \(\dfrac{5}{3}\)
2 - 3 \(\times\) y = \(\dfrac{8}{15}\)
3 \(\times\) y = 2 - \(\dfrac{8}{15}\)
3 \(\times\) y = \(\dfrac{22}{15}\)
y = \(\dfrac{22}{15}\) : 3
y = \(\dfrac{22}{45}\)
( 2 x y + 2/15 ) x 3 = 4/5
( 2 x y + 2/15 ) = 4/5 : 3
( 2 x y + 2/15 ) = 4/15
2 x y = 4/15 - 2/15
2 x y = 2/15
y = 2/15 :2
y = 1/15
(2 x y + 2/15) x 3 = 4/5
2 x y + 2/15) = 4/5 : 3
2 x y + 2/15 = 4/15
2 x y = 4/15 - 2/15
2 x y = 2/15
y = 2/15 : 2
y = 1/15
7/9 x (2 - 1/3 x y) = 14/15
(2 - 1/3 x y) = 14/15 : 7/9
(2 - 1/3 x y) = 6/5
2 - y = 6/5 x 1/3
2 - y = 2/5
y = 2/5 + 2
y = 12/5
4/21 + 5 x y - 8/7 = 1/3
4/21 + 5 x y = 1/3 + 8/7
4/21 + 5 x y = 31/21
5 x y = 31/21 - 4/21
5 x y = 9/7
y = 9/7 : 5
y = 9/35
7/12 x y - 3/12 x y = 5
y x (7/12 - 3/12) = 5
y x 1/3 = 5
y = 5 : 1/3
y = 15
\(2,\frac{9}{x}=\frac{2}{5}-\frac{7}{20}\)
\(\Rightarrow\frac{9}{x}=\frac{1}{20}\)
\(\Rightarrow x=9.20\)
\(\Rightarrow x=180\)
\(\frac{x}{5}=\frac{5}{6}+\left(-\frac{19}{30}\right)\)
\(\frac{\Rightarrow x}{5}=\frac{1}{5}\)
\(\Rightarrow x=1\)
1)\(\left(x+1\right).\left(y-2\right)=0\) \(\left(x,y\inℤ\right)\)
\(\Rightarrow\orbr{\begin{cases}x+1=0\\y-2=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=-1\\y=2\end{cases}}\)
2)\(\left(x-5\right).\left(y-7\right)=1\)
| x-5 | 1 | -1 |
| y-7 | 1 | -1 |
| x | 6 | 4 |
| y | 8 | 6 |
3)\(\left(x+4\right).\left(y-2\right)=2\)
| x+4 | 1 | 2 | -1 | -2 |
| y-2 | 2 | 1 | -2 | -1 |
| x | -3 | -2 | -5 | -6 |
| y | 4 | 3 | 0 | 1 |
4)\(\left(x-4\right).\left(y+3\right)=-3\)
| x-4 | 1 | -1 | 3 | -3 |
| y+3 | -3 | 3 | -1 | 1 |
| x | 5 | 3 | 7 | 1 |
| y | -6 | 0 | -4 | -2 |
5)\(\left(x+3\right).\left(y-6\right)=-4\)
| x+3 | -1 | 1 | -4 | 4 | 2 | -2 |
| y-6 | 4 | -4 | 1 | -1 | -2 | 2 |
| x | -4 | -2 | -7 | 1 | -1 | -5 |
| y | 10 | 2 | 7 | 5 | 4 | 8 |
6)\(\left(x-8\right).\left(y+7\right)=5\)
| x-8 | 1 | 5 | -1 | -5 |
| y+7 | 5 | 1 | -5 | -1 |
| x | 9 | 13 | 7 | 3 |
| y | -2 | -6 | -12 | -8 |
7)\(\left(x+7\right).\left(y-3\right)=-6\)
| x+7 | -1 | 1 | -6 | 6 | -2 | 2 | -3 | 3 |
| y-3 | 6 | -6 | 1 | -1 | 3 | -3 | 2 | -2 |
| x | -8 | -6 | -13 | -1 | -9 | -5 | -10 | -4 |
| y | 9 | -3 | 4 | 2 | 6 | 0 | 5 | 1 |
8)\(\left(x-6\right).\left(y+2\right)=7\)
| x-6 | 1 | 7 | -1 | -7 |
| y+2 | 7 | 1 | -7 | -1 |
| x | 7 | 13 | 5 | -1 |
| y | 5 | -1 | -9 | -3 |
ok :)
1: (x+1)(y+2)=5
mà y+2>=2(do y là số tự nhiên)
nên (x+1;y+2)∈(1;5)
=>(x;y)∈(0;3)
2: (x+1)(y+2)=6
mà x+1>=1 và y+2>=2(do x,y là các số tự nhiên)
nên (x+1;y+2)∈{(3;2);(2;3);(1;6)}
=>(x;y)∈{(2;0);(1;1);(0;4)}
3: (x+2)(y+3)=6
mà x+2>=2 và y+3>=3(do x,y là các số tự nhiên)
nên (x+2;y+3)∈{(2;3)}
=>(x;y)∈(0;0)
4: (x-1)(y+3)=6
mà y+3>=3(do y là số tự nhiên)
nên (x-1;y+3)∈{(2;3);(1;6)}
=>(x;y)∈{(3;0);(2;3)}
5: (x-1)(y-3)=5
=>(x-1;y-3)∈{(1;5);(5;1)}
=>(x;y)∈{(4;8);(6;4)}
6: (x-2)(y-1)=3
=>(x-2;y-1)∈{(1;3);(3;1)}
=>(x;y)∈{(3;4);(5;2)}
7: (x-2)(y-1)=5
=>(x-2;y-1)∈{(1;5);(5;1)}
=>(x;y)∈{(3;6);(7;2)}
8: (x-3)(y+1)=7
mà y+1>=1(do y là số tự nhiên)
nên (x-3;y+1)∈{(1;7);(7;1)}
=>(x;y)∈{(4;6);(10;0)}