1.

suppose , and let be a continuous complex valued function on the product space assume that for each , the function is analytic on define F on Ω by and F is analytic on Ω and ​

Answer»

Correct Question:

suppose \large\rm { [a,b] \subseteq \mathbb{R}} , and LET \large\rm { \varphi} be a CONTINUOUS complex valued FUNCTION on the product space \large\rm { Ω \times [a,b]} assume that for each \large\rm { t \in [a,b]} , the function \large\rm { z \longrightarrow \varphi (z,t)} is analytic on \large\rm{ Ω} define F on Ω by \large\rm { F(z) = \displaystyle\int_{a}^{b} \varphi (z,t) dt, z \in Ω} and F is analytic on Ω and \large\rm { F'(z) = \displaystyle\int_{a}^{b} \frac{\partial \varphi}{\partial z} (z,t) dt , z \in Ω}

Proof:

FIX any disk \large\rm{ D(z_{0} , r)} such that \large\rm { \bar{D} (z_{0}, r) \subseteq Ω} . Then for each \large\rm { z \in D (z_{0} , r)},

\large\rm { F(z) = \displaystyle\int_{a}^{b} \varphi (z,t) dt}

\small\rm{ = \frac{1}{2 \pi i} \displaystyle\int_{a}^{b} \Bigg\lgroup \displaystyle\int_{C(z_{0} ,r)}  \frac{\varphi (w,t)}{w-z} dw \Bigg\rgroup dt}

\small\rm{ = \frac{1}{2 \pi i} \displaystyle\int_{C(z_{0} , r)} \Bigg\lgroup  \displaystyle\int_{a}^{b} \varphi(w,t) dt \bigg\rgroup \frac{1}{w-z} dw}

\small\rm { F'(z) = \frac{1}{2 \pi i} \displaystyle\int_{C(z_{0} , r)} \Bigg [ \displaystyle\int_{a}^{b} \varphi(w,t) dt \Bigg ] \frac{1}{(w-z)^{2}} dw}

\small\rm { = \displaystyle\int_{a}^{b} \Bigg [  \frac{1}{2 \pi i} \displaystyle\int_{C(z_{0} ,r)}  \frac{\varphi (w,t)}{(w-z)^{2}} dw \Bigg ] dt}

\large\rm { = \displaystyle\int_{a}^{b} \frac{\partial \varphi}{\partial z} (z,t) dt  }

HENCE proven.



Discussion

No Comment Found

Related InterviewSolutions