Xav paub tias daim duab ntawm kev ua haujlwm yog ib txoj kab ncaj nraim, qhov no tsis tsim nyog, puas yog? Yog li ntawd, tsis muaj qhov taw qhia ntawm concavity ntawm cov duab ntawm cov kab khiav haujlwm.
Txoj kab ncaj nraim puas muaj qhov sib npaug?
Kev sib kis tau los ntawm ob hom, nce thiab nqis. Qhov no yog ib yam khoom uas peb koom nrog x-intervals, yog li daim duab yuav raug concave rau ib pliag, thiab tom qab ntawd hloov mus rau concave down. Cia peb pib nrog ob peb txoj kab ncaj nraim, ib qho nce thiab ib qho zuj zus. Ib txoj kab ncaj nraim tsis concave los yog concave down
Cov kab ntu puas muaj qhov sib txawv?
A kev ua haujlwm ntawm ib qho kev sib txawv yog concave yog tias txhua ntu ntu koom nrog ob lub ntsiab lus ntawm nws daim duab tsis nyob saum daim duab ntawm ib qho twg. Symmetrically, ib qho kev ua haujlwm ntawm ib qho kev sib txawv yog convex yog tias txhua kab ntu koom nrog ob lub ntsiab lus ntawm nws daim duab tsis nyob hauv qab daim duab ntawm ib qho taw tes.
Cov kab linear puas tuaj yeem ua rau nce lossis nqis?
A kab ncaj yog txais tau rau kev sib tw nce toj lossis concave downward. Tab sis thaum peb siv cov ntsiab lus tshwj xeeb nruj me ntsis concave upward los yog nruj me ntsis concave downward ces ib tug ncaj kab tsis OK.
Koj paub li cas yog qhov ua haujlwm yog concave nce lossis nqis?
Yog f "(x) > 0, daim duab yog concave upward ntawm tus nqi ntawm x. Yog tias f "(x)=0, daim duab yuav muaj ib qho taw tes ntawm inflection ntawm tus nqi ntawm x. Txhawm rau txheeb xyuas, xav txog tus nqi ntawm f "(x) ntawm qhov tseem ceeb ntawm x rau ob sab ntawm qhov kev txaus siab. Yog tias f "(x) < 0, daim duab yog concave downwardntawm tus nqi ntawm x.
