Toán Lớp 7: xy-x+2(y-1)=2
Nhanh giúp e vs ạ
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Toán Lớp 7: xy-x+2(y-1)=2
Nhanh giúp e vs ạ
Comments ( 2 )
Giải đáp:
xy-x+2.(y-1)=2
-> x.(y – 1) + 2.(y -1) = 2
-> (y- 1).(x + 2) = 2
Do: x , y ∈ ZZ
-> x + 2; y – 1 ∈ ZZ
-> x + 2; y – 1 ∈ Ư_{(2)} = {1; -1;2 ; -2}
Lập bảng giá trị
\begin{array}{|c|c|c|}\hline \text{x + 2}&\text{1}&\text{-1}&\text{2}&\text{-2}\\\hline \text{y- 1}&\text{2}&\text{-2}&\text{1}&\text{-1}\\\hline \text{x}&\text{-1}&\text{-3}&\text{0}&\text{-4}\\\hline \text{y}&\text{3}&\text{-1}&\text{2}&\text{0}\\\hline\end{array}
Vậy (x; y) = (-1,3); (-3, -1); (0,2); (-4,0)
$#dariana$
text{Giải đáp + Lời giải và giải thích chi tiết :}
xy – x + 2(y – 1) = 2
xy – x + 2(y – 1) – 2(y – 1) = 2 – 2(y – 1)
xy – x = -2y + 4
x – (y – 1) = -2y + 4
(x^((y-1))/(y-1)) = -(2y)/(y-1) + 4/(y-1)
=> x = (-2y + 4)/(y-1) ; y ne 1
text{#Muối}