Question

若z₁=a+3i，z₂=3+4i，且

z1

z2

为纯虚数，则实数a=______．

Answer 1

z1

z2

=

a+3i

3+4i

=

(a+3i)(3-4i)

(3+4i)(3-4i)

=

(3a+12)+(9-4a)i

25

，∴

3a+12=0 9-4a≠0

解得a=-4
故答案为：-4