设 z = a + bi,a,b为实数.z + 10/z = a + bi + 10/(a+bi)= a + bi + 10(a-bi)/[a^2 + b^2]= a + 10a/[a^2 + b^2] + {b - 10b/[a^2 + b^2]}ib[a^2 + b^2 - 10] = 0....(1)1 < a + 10a/[a^2 + b^2] 0.a + 10/a >= 2(a*...