Asosiy tarkibga o'tish

2.5-bo'lim : Hisoblash chegaralari

Berilgan \[h\left( z \right) = \left\{ {\begin{array}{rc}{6z}&{z \le - 4}\\{1 - 9z}&{z > - 4}\end{array}} \right.\]

11. Quyidagi chegaralarni, agar ular mavjud bo'lsa, baholang.

  1. \(\mathop {\lim }\limits_{z \to 7} h\left( z \right)\)
  2. \(\mathop {\lim }\limits_{z \to - 4} h\left( z \right)\)

a \(\mathop {\lim }\limits_{z \to 7} h\left( z \right)\) Yechim

Ushbu qism uchun biz \(7 > - 4\) va shuning uchun \(z > - 4\) diapazonida 7 ning ikkala tomonida \(z\) qiymatlari bo'lishini bilamiz va shuning uchun biz chegarada \(z > - 4\)ga ega bo'lamiz deb taxmin qilishimiz mumkin. Bu bizga ushbu diapazondagi funktsiya qismini ishlatishga imkon beradi va keyin chegarani hisoblash uchun standart chegara usullaridan foydalaning.

\[\mathop {\lim }\limits_{z \to 7} h\left( z \right) = \mathop {\lim }\limits_{z \to 7} \left( {1 - 9z} \right) = \require{bbox} \bbox[2pt,border:1px solid black]{{ - 62}}\]

b \(\mathop {\lim }\limits_{z \to - 4} h\left( z \right)\) Yechim

Bu qism oldingi qismdan farq qiladi. Biz \(z = - 4\)-dagi chegarani ko'rib chiqamiz va bu qismlarga bo'lingan funktsiyalardagi "kesish" nuqtasidir. Bo'limdagi muhokamadan eslang, bu biz ikkita bir tomonlama chegaralarni ko'rib chiqishimiz kerakligini anglatadi.

\[\mathop {\lim }\limits_{z \to \, - {4^{\, - }}} h\left( z \right) = \mathop {\lim }\limits_{z \to \, - {4^{\, - }}} 6z = \underline { - 24} \hspace{0.25in}\hspace{0.25in}{\mbox{because }}z \to - {4^ - }{\mbox{ implies that }}z < - 4\] \[\mathop {\lim }\limits_{z \to \, - {4^{\, + }}} h\left( z \right) = \mathop {\lim }\limits_{z \to \, - {4^{\, + }}} \left( {1 - 9z} \right) = \underline {37} \hspace{0.25in}{\mbox{because }}z \to - {4^ + }{\mbox{ implies that }}z > - 4\]

Shunday qilib, bu holatda biz buni ko'rishimiz mumkin,

\[\mathop {\lim }\limits_{z \to \, - {4^{\, - }}} h\left( z \right) = - 24 \ne 37 = \mathop {\lim }\limits_{z \to \, - {4^{\, + }}} h\left( z \right)\]

va shuning uchun biz umumiy chegara ekanligini bilamiz mavjud emas.