题目
2.4.10 证明下面u或v为调和函数,并求解析函数f(z)=u+iv:(a)u=x³-3xy²; (b)u=x²-y²+2x;(c)u=(x)/(x^2)+y^(2); (d)u=(x)/(x^2)+y^(2)-2y;(e)u=2e^xsin y; (f)v=2xy+3x;(g)v=(-y)/((x+1)^2)+y^(2); (h)v=arctan(y)/(x),x>0;(i)v=e^x(y cos y+x sin y)+x+y;(j)v=(y)/(x^2)+y^(2),f(2)=0.
2.4.10 证明下面u或v为调和函数,并求解析函数f(z)=u+iv:
(a)u=x³-3xy²; (b)u=x²-y²+2x;
(c)$u=\frac{x}{x^{2}+y^{2}}$; (d)$u=\frac{x}{x^{2}+y^{2}}-2y$;
(e)$u=2e^{x}sin y$; (f)v=2xy+3x;
(g)$v=\frac{-y}{(x+1)^{2}+y^{2}}$; (h)$v=arctan\frac{y}{x},x>0$;
(i)v=e^{x}(y cos y+x sin y)+x+y;
(j)$v=\frac{y}{x^{2}+y^{2}},f(2)=0$.
题目解答
答案
(a) $u = x^3 - 3xy^2$,满足调和方程,$f(z) = z^3$。
(b) $u = x^2 - y^2 + 2x$,满足调和方程,$f(z) = z^2 + 2z$。
(c) $u = \frac{x}{x^2 + y^2}$,满足调和方程,$f(z) = \frac{1}{z}$。
(d) $u = \frac{x}{x^2 + y^2} - 2y$,满足调和方程,$f(z) = \frac{1}{z} - 2iz$。
(e) $u = 2e^x \sin y$,满足调和方程,$f(z) = 2ie^z$。
(f) $v = 2xy + 3x$,满足调和方程,$f(z) = -iz^2 - 3iz$。
(g) $v = \frac{-y}{(x+1)^2 + y^2}$,满足调和方程,$f(z) = \frac{i}{z+1}$。
(h) $v = \arctan \frac{y}{x}$,满足调和方程,$f(z) = i \ln z$。
(i) $v = e^x (y \cos y + x \sin y) + x + y$,满足调和方程,$f(z) = ze^z + iz$。
(j) $v = \frac{y}{x^2 + y^2}$,满足调和方程,$f(z) = -\frac{i}{z}$。
\[
\boxed{
\begin{array}{ll}
(a) & z^3 \\
(b) & z^2 + 2z \\
\vdots \\
(j) & -\frac{i}{z} \\
\end{array}
}
\]