Ib ntus uas ib qho kawg suav nrog tab sis tsis yog lwm qhov. Ib nrab-kaw lub sijhawm yog qhia lossis thiab tseem hu ua ib nrab-qhib lub sijhawm.
Lub sijhawm kaw txhais li cas?
Ib lub sijhawm kaw yog ib qho uas suav nrog nws cov ntsiab lus kawg: piv txwv li, lub teeb {x | −3≤x≤1}. Txhawm rau sau lub sijhawm no nyob rau hauv lub sijhawm sau tseg, peb siv cov kab kaw : [−3, 1] Lub sijhawm qhib yog ib qho uas tsis suav nrog nws qhov kawg, piv txwv li, {x | −3<x<1}.
Puas yog ib nrab qhib lub sijhawm kaw?
Ib nrab qhib ncua sij hawm (a, b] tsis yog qhib lossis kaw.
Lub sijhawm qhib thiab kaw ib nrab yog dab tsi?
Yog a thiab b yog ob tus lej tiag xws li < b, ces the sets (a, b]={ x: x ∈ R, a < x ≤ b} thiab [a, b)={ x:x ∈ R, a ≤ x < b yog hu ua semi-open lossis semi-kaw intervals.
Yuav ua li cas kaw cov ntu hauv lej?
Ib lub sijhawm kaw suav nrog nws cov ntsiab lus kawg thiab suav nrog square brackets es tsis yog kab lus. Piv txwv li, [0, 1] piav txog lub caij nyoog ntau dua lossis sib npaug ntawm 0 thiab tsawg dua lossis sib npaug rau 1. Txhawm rau qhia tias tsuas yog ib qho kawg ntawm ib ntus suav nrog hauv qhov teeb tsa, ob lub cim yuav raug siv.
