Question

Tìm x ; y \(\in\) Z biết :

a. -(x - 3) + 2 . ( -3 ) = 1

b. ( x + 1 ) . ( y -2 ) = 11

c. ( y + 3 ) . ( 2x - 10 ) = 0

Answer 1

a. -(x-3)+2.(-3)=1

\(\Leftrightarrow\)-x+3-6=1

\(\Leftrightarrow\)x=-4

b.(x+1).(y-2)=11

\(\Rightarrow\)x+1 và y-2 \(\in\)Ư₍₁₁₎=\(\left\{1;-1;11;-11\right\}\)

Ta có:

\(\left\{\begin{matrix}x+1=1\\x+1=-1\\x+1=11\\x+1=-11\end{matrix}\right.\)\(\Leftrightarrow\left\{\begin{matrix}x=0\\x=-2\\x=10\\x=-12\end{matrix}\right.\Leftrightarrow\left\{\begin{matrix}y=13\\y=-9\\y=3\\y=1\end{matrix}\right.\)

Vậy: x=0 thì y=13; x=-2 thì y=-9;x=10 thì y=3; x=-12 thì y=1

c.(y+3)(2x-10)=0

\(\Leftrightarrow\)y+3=0 hoặc 2x-10=0

1, y+3=0\(\Rightarrow\)y=-3

2, 2x-10=0\(\Rightarrow\)x=5