Question

tìm x,y là số tự nhiên sao cho

a) ( 2x + 1 ) . ( y - 3 ) =10

b) ( 3x - 2 ) . ( 2y - 3 ) =1

c) ( x + 1 ) . ( 2y - 1 ) = 12

d) x + 6 = y . ( x - 1 )

e) x - 3 = y . ( x +2 )

Answer 1

[ Mik phải giỏi hơn đứa mik ghét ;) ]

a) Dễ thấy \(2x+1⋮̸\) \(2\)

\(\Rightarrow\) \(\left(2x+1\right).\left(y-3\right)=10=1.10=5.2\)

\(\Leftrightarrow\left[{}\begin{matrix}2x+1=1;y-3=10\\2x+1=5;y-3=2\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0;y=13\\x=2;y=5\end{matrix}\right.\)

Vậy \(\left(x;y\right)\in\left\{\left(0;13\right);\left(2;5\right)\right\}\)

b) \(\left(3x-2\right)\left(2y-3\right)=1\)\(=1.1\)

\(\Leftrightarrow3x-2=1;2y-3=1\)

\(\Leftrightarrow x=1;y=2\)

Vậy: \(\left(x;y\right)=\left(1;2\right)\)