Chương II : Số nguyên

`1/7+(-9/27)+10/7+(-4/7)`

`= (1/7 + (-4)/7+10/7) +(-9/27)`

`= 7/7 +(-9/27)`

`= 1 +(-9/27)`

`= 27/27 + (-9/27)`

`=18/27`

`=2/3`

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`1,3 xx2 1/4 -1,3 xx3 1/4`

`= 1,3 xx 9/4 -1,3 xx 13/4`

`=1,3 xx (9/4-13/4)`

`=1,3xx(-4)/4`

`=1,3 xx (-1)`

`=-1,3`

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`1/4: x = 2,4 -4/5`

`=> 1/4 : x= 12/5 -4/5`

`=> 1/4 : x=8/5`

`=> x=1/4 : 8/5`

`=> x= 1/4 xx 5/8`

`=> x= 5/32`

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`5/4 ( x- 3/5)= -1/8`

`=> x-3/5 = -1/8 : 5/4`

`=> x-3/5 = -1/8 xx 4/5`

`=> x-3/5 =-4/40`

`=> x-3/5 =-1/10`

`=> x=-1/10 +3/5`

`=> x=-1/10 + 6/10`

`=> x= 5/10`

`=>x=1/2`

` @ yngoc`

\(\overline{ab9}=\overline{ab}+522\)

\(\Rightarrow10.\overline{ab}+9=\overline{ab}+522\)

\(\Rightarrow10\overline{ab}-\overline{ab}=522-9\)

\(\Rightarrow9\overline{ab}=513\)

\(\Rightarrow\overline{ab}=\dfrac{513}{9}=57\)

Vậy số ab là số 57

a: n=3-5=-2

b: =>-3n-2n=1-2

=>-5n=-1

=>n=1/5(loại)

a: =39-13-62-39=-75

b: =(-2)+(-2)+(-2)=-6

c: 92-55+8-45=100-100=0

d: M={-20;-19;-18;...;18;19;20}

Tổng là (-20)+(-19)+(-18)+...+18+19+20=0

\(2x+xy+y=5\)

\(x\left(2+y\right)+\left(y+2\right)-2=5\)

\(\left(2+y\right).\left(x+1\right)=5+2\)

\(\left(2+y\right).\left(x+1\right)=7\)

\(=>\left[{}\begin{matrix}2+y=-7\\x+1=-1\end{matrix}\right.=>\left[{}\begin{matrix}y=-9\\x=-2\end{matrix}\right.\)

       \(\left[{}\begin{matrix}2+y=-1\\x+1=-7\end{matrix}\right.=>\left[{}\begin{matrix}y=-3\\x=-8\end{matrix}\right.\)

       \(\left[{}\begin{matrix}2+y=1\\x+1=7\end{matrix}\right.=>\left[{}\begin{matrix}y=-1\\x=6\end{matrix}\right.\)

       \(\left[{}\begin{matrix}2+y=7\\x+1=1\end{matrix}\right.=>\left[{}\begin{matrix}y=5\\x=0\end{matrix}\right.\)

Vậy ta có 4 cặp x,y: \(x=-2;y=-9\)

                                \(x=-8;y=-3\)

                                \(x=6;y=-1\)

                                \(x=0;y=5\)

Giúp tôi!!!!

=>3n+12+4 chia hết cho n+4

=>\(n+4\in\left\{1;-1;2;-2;4;-4\right\}\)

=>\(n\in\left\{-3;-5;-2;-6;0;-8\right\}\)

Giúp mik vs .

(a-2)(b+1) = 5

vì a,b ∈ z nên (a-2)(b+1) = 5 

\(\Leftrightarrow\) th1 :  \(\left\{{}\begin{matrix}a-2=-1\\b+1=-5\end{matrix}\right.\) => \(\left\{{}\begin{matrix}a=1\\b=-6\end{matrix}\right.\)

     th2:    \(\left\{{}\begin{matrix}a-2=1\\b+1=5\end{matrix}\right.\)   => \(\left\{{}\begin{matrix}a=3\\b=4\end{matrix}\right.\)

    th3 :    \(\left\{{}\begin{matrix}a-2=-5\\b+1=-1\end{matrix}\right.\) => \(\left\{{}\begin{matrix}a=-3\\b=-2\end{matrix}\right.\)

    th4:     \(\left\{{}\begin{matrix}a-2=5\\b+1=1\end{matrix}\right.\)   => \(\left\{{}\begin{matrix}a=7\\b=0\end{matrix}\right.\)

Kết luận (a;b) = (1; -6); ( 3; 4); (-3; -2); ( 7; 0)

\(\left(-512\right)-\left(x-18\right):2=-16\)

\(\left(x-18\right):2=-496\)

\(x-18=-992\)

\(x=-974\)

=>x+1-7 chia hết cho x+1

=>\(x+1\in\left\{1;-1;7;-7\right\}\)

mà x là số nguyên âm lớn nhất

nên x=-2