Per igualar, escrivim les dues equacions explícites i igualem per calcular x: 

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mrow mathcolor=¨#003300¨»«mfenced open=¨{¨ close=¨}¨»«mtable»«mtr»«mtd»«mi mathsize=¨12px¨ mathvariant=¨bold¨»y«/mi»«mo mathsize=¨12px¨ mathvariant=¨bold¨»=«/mo»«mn mathsize=¨12px¨ mathvariant=¨bold¨»3«/mn»«mi mathsize=¨12px¨ mathvariant=¨bold¨»x«/mi»«mo mathsize=¨12px¨ mathvariant=¨bold¨»+«/mo»«mn mathsize=¨12px¨ mathvariant=¨bold¨»2«/mn»«/mtd»«/mtr»«mtr»«mtd»«mi mathsize=¨12px¨ mathvariant=¨bold¨»y«/mi»«mo mathsize=¨12px¨ mathvariant=¨bold¨»=«/mo»«mo mathsize=¨12px¨ mathvariant=¨bold¨»-«/mo»«mn mathsize=¨12px¨ mathvariant=¨bold¨»2«/mn»«mi mathsize=¨12px¨ mathvariant=¨bold¨»x«/mi»«mo mathsize=¨12px¨ mathvariant=¨bold¨»-«/mo»«mn mathsize=¨12px¨ mathvariant=¨bold¨»3«/mn»«/mtd»«/mtr»«/mtable»«/mfenced»«mo mathsize=¨12px¨ mathvariant=¨bold¨»§#8660;«/mo»«mn mathsize=¨12px¨ mathvariant=¨bold¨»3«/mn»«mi mathsize=¨12px¨ mathvariant=¨bold¨»x«/mi»«mo mathsize=¨12px¨ mathvariant=¨bold¨»+«/mo»«mn mathsize=¨12px¨ mathvariant=¨bold¨»2«/mn»«mo mathsize=¨12px¨ mathvariant=¨bold¨»=«/mo»«mo mathsize=¨12px¨ mathvariant=¨bold¨»-«/mo»«mn mathsize=¨12px¨ mathvariant=¨bold¨»2«/mn»«mi mathsize=¨12px¨ mathvariant=¨bold¨»x«/mi»«mo mathsize=¨12px¨ mathvariant=¨bold¨»-«/mo»«mn mathsize=¨12px¨ mathvariant=¨bold¨»3«/mn»«mo mathsize=¨12px¨ mathvariant=¨bold¨»§#8660;«/mo»«mn mathsize=¨12px¨ mathvariant=¨bold¨»5«/mn»«mi mathsize=¨12px¨ mathvariant=¨bold¨»x«/mi»«mo mathsize=¨12px¨ mathvariant=¨bold¨»=«/mo»«mo mathsize=¨12px¨ mathvariant=¨bold¨»-«/mo»«mn mathsize=¨12px¨ mathvariant=¨bold¨»5«/mn»«mo mathsize=¨12px¨ mathvariant=¨bold¨»§#8660;«/mo»«mi mathsize=¨12px¨ mathvariant=¨bold¨»x«/mi»«mo mathsize=¨12px¨ mathvariant=¨bold¨»=«/mo»«mo mathsize=¨12px¨ mathvariant=¨bold¨»-«/mo»«mn mathsize=¨12px¨ mathvariant=¨bold¨»1«/mn»«/mrow»«mstyle mathvariant=¨bold¨ mathcolor=¨#003300¨ mathsize=¨12px¨/»«/math»

Per calcular y, substituïm  x per (-1) en qualsevol de les dues equacions: y = 3·(-1) + 2 = -1 i es tallen en el punt (-1,-1).

Si dona 0x=0, són coincidents.

Si dona 0x≠0, són paral·leles.