Question

设z是虚数,w=z+(1/z)是实数,且-1

Answer 1

令z=x+yi,则w=z+1/z=x+yi+(x-yi)/√(x²+y²)=[x+x/√(x²+y²)]+[y-y/√(x²+y²)]i

因为w是实数且-1