问题
解答题
若|z|=1,且z2+2z+
|
答案
设z=a+bi,
|z|=1有a2+b2=1
∵z2+2z+
为负实数1 z
∴z2+2z+
=(a2-b2+3a)+(2ab+b)i+(2ab+b)i1 z
2ab+b=0,a2-b2+3a<0
∴z=-
+1 2
i3 2
z=-
-1 2
i3 2
z=-1
故复数是z=-
+1 2
i或z=-3 2
-1 2
i或z=-13 2
若|z|=1,且z2+2z+
|
设z=a+bi,
|z|=1有a2+b2=1
∵z2+2z+
为负实数1 z
∴z2+2z+
=(a2-b2+3a)+(2ab+b)i+(2ab+b)i1 z
2ab+b=0,a2-b2+3a<0
∴z=-
+1 2
i3 2
z=-
-1 2
i3 2
z=-1
故复数是z=-
+1 2
i或z=-3 2
-1 2
i或z=-13 2