Toán Lớp 6: Tìm x,y ∈ ZZ biết :
( x – 1 ) ( y + 5 ) = 7
Leave a reply
Register Now
Login
Lost Password
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Toán Lớp 6: Tìm x,y ∈ ZZ biết :
( x – 1 ) ( y + 5 ) = 7
Comments ( 2 )
Giải đáp:
( x – 1 ).( y + 5 ) = 7
Vì x,y ∈ ZZ
-> x – 1, y + 5 ∈ ZZ
-> x – 1. y + 5 ∈ Ư_{(7)} = {1; -1;7;-7}
Lập bảng giá trị
\begin{array}{|c|c|c|}\hline \text{x – 1}&\text{1}&\text{-1}&\text{7}&\text{-7}\\\hline \text{y + 5}&\text{7}&\text{-7}&\text{1}&\text{-1}\\\hline \text{x}&\text{2}&\text{0}&\text{8}&\text{-6}\\\hline \text{y}&\text{2}&\text{-12}&\text{-4}&\text{-6}\\\hline\end{array}
Vậy (x,y) = (2,2);(0,-12);(8, -4); (-6,-6)
$#dairana$
(x-1).(y+5)=7
=>(x-1).(y+5)=(-1).(-7)=(-7).(-1)=1.7=7.1=7
Ta có bảng sau:
\begin{array}{|c|c|c|}\hline \text{$x-1$}&\text{$1$}&\text{$-1$}&\text{$7$}&\text{$-7$}\\\hline \text{$y+5$}&\text{$7$}&\text{$-7$}&\text{$1$}&\text{$-1$}\\\hline \text{$x$}&\text{$2$}&\text{$0$}&\text{$8$}&\text{$-6$}\\\hline \text{$y$}&\text{$2$}&\text{$-12$}&\text{$-4$}&\text{$-6$}\\\hline\end{array}
Vậy x in {2;0;8;-6};y in {2;-12;-4;-6}