3.4  Hubin

Marka isla’eg la xalliyo, waxaa si fudud loo hubin karaa in la helay xidid sax ah iyo in kale. Taa waxaa loo samayn karaa iyadoo qiimaha xididka lagu beddelo booska doorsoomaha.

Ka soo qaad tusaale ahaan inaad xallisay isla’egta 5 – 6x = x + 1,5 kadibna heshay x = 0,5.

Hubinta waxaa loo samayn karaa iyadoo lagu beddelo x = 0,5 kadibna la fiiriyo in DHB = DHM

DHB = 5 – 6 ∙ 0,5 = 5 – 3 = 2
DHM = 0,5 + 1,5 = 2

DHB = DHM hadaba x = 0,5 waa xididka isle’egta.

Tusaale: x = 6 ma tahay xididka isla’egta 4x + 3 = x/2 + 25 ?

Hubi adiga oo ku beddelaya x = 6:

DHB = 4 ∙ 6 + 3 = 24 + 3 = 27
DHM = 6/2 + 25 = 3 + 25 = 28

DHB ≠ DHM sidaa darteed x = 6 ma ahan xididka isle’egta.

Tusaale: Isla’egta x4 – 2401 = 0 waxaa lagu xalliyey natiijada x = –7.

DHB = (–7)4 – 2401 = 2401 – 2401 = 0
DHM = 0

DHB = DHM sidaa darteed x = –7 waa xididka isle’egta.

Taas macnaheedu ma ahan in x = –7 ay tahay xididka kaliya ee isla’egta. Sidaa darteed la ma oran karo isla’egta waa la xalliyey iyadoo la adeegsanayo hubinta. Kaliya hubintu waa mid inoo sahlaysa in la helo xidid walba markiisa.

 Ka feker kalana dood kooxda kale: Ma leedahay isla’egta kore dhowr xidid oo kale oo aan ahayn x = –7.  Hadday jiraan waa kuwee?