Question

Tìm x,y biết(làm 4 cách)

a)(x-2).(2y+1)=17

b)xy+x+2y=5

Answer 1

a: (x-2)(2y+1)=17

\(\Leftrightarrow\left(x-2;2y+1\right)\in\left\{\left(1;17\right);\left(17;1\right);\left(-1;-17\right);\left(-17;-1\right)\right\}\)

hay \(\left(x,y\right)\in\left\{\left(3;8\right);\left(19;0\right);\left(1;-9\right);\left(-15;-1\right)\right\}\)

b: \(\Leftrightarrow xy+x+2y+2=7\)

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

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

\(\Leftrightarrow\left(x+2;y+1\right)\in\left\{\left(1;7\right);\left(7;1\right);\left(-1;-7\right);\left(-7;-1\right)\right\}\)

hay \(\left(x,y\right)\in\left\{\left(-1;6\right);\left(5;0\right);\left(-1;-8\right);\left(-9;-2\right)\right\}\)