Hệ pt 3x+2y=36 (x-2)(y-3)=18

⇔3x+2y=36; xy-2y-3x+6=18

⇔3x+2y=36; xy-36+6=18 (3x+2y=36)

⇔3x+2y=36 ; xy=48

⇔3x+2y=36; x=48/y

⇔144/y+2y=36; x=48/y

⇔2y^2-36y+144=0; x=48/y

⇔y=12 hoặc y=6 ; x=48/y

⇔ (x;y)= (4;12) và (8;6)