Dab tsi ua rau muaj nuj nqi Surjective?
Dab tsi ua rau muaj nuj nqi Surjective?

Video: Dab tsi ua rau muaj nuj nqi Surjective?

Video: Dab tsi ua rau muaj nuj nqi Surjective?
Video: Functia compusa radical indice 2600 2024, Kaum ib hlis
Anonim

Hauv lej, a muaj nuj nqi f los ntawm lub teeb X rau aset Y yog qhov tseeb (tseem hu ua onto, los yog ib tug surjection), yog hais tias rau txhua lub caij y nyob rau hauv lub codomain Y ntawm f, muaj tsawg kawg yog ib lub caij x nyob rau hauv lub sau X ntawm f xws li f(x) = y.

Tsuas yog li ntawd, koj yuav ua li cas paub yog tias muaj nuj nqi yog Surjective?

Qhov tseeb (Kuj hu ua "Onto") A muaj nuj nqi f (los ntawm teeb A mus rau B) yog qhov tseeb Yog tias thiab tsuas yog rau txhua y hauv B, tsawg kawg yog ib x hauv A xws li f (x) = y, hauv lwm lo lus f yog qhov tseeb yog thiab tsuas yog f(A) = B.

Tsis tas li ntawd, koj yuav ua li cas paub yog tias muaj nuj nqi yog graphically? Rau ib-ib qho: tsuas yog cov kab kos duab (perpendicular rau x-axis) ces yog tias koj pom cov kab sib tshuam ntawm qhov nkhaus ntawm muaj nuj nqi tiam no tsis yog ib leeg. Raws li rau ib-ib txoj kab ntsug yuav tsum sib tshuam nrog rau daim duab ntawm muaj nuj nqi ntawm ib qho!

Ua li no, nws txhais li cas rau kev ua haujlwm ua Surjective?

Cov muaj nuj nqi yog surjective (mus rau) yog tias txhua lub ntsiab lus ntawm lub codomain yog mapped los ntawm yam tsawg kawg ib lub ntsiab ntawm lubdomain. (Qhov ntawd yog , daim duab thiab lub codomain ntawm lub muaj nuj nqi yog sib.) A surjective muaj nuj nqi yog kev txiav txim siab.

Muaj pes tsawg lub luag haujlwm yog Surjective?

Tsim ib tug muaj nuj nqi Los ntawm A mus rau B, rau txhua yam hauv A koj yuav tsum xaiv ib lub caij hauv B. Muaj 3 txoj hauv kev xaiv txhua yam ntawm 5 lub ntsiab = muaj nuj nqi . Tab sis peb xav surjective functions.

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