i是虚数单位,i+2i^2+3i^3+……+2007i^2007=?

解：i+2i²+3i³+4i^4=i-2-3i+4=2-2i 5i^5+6i^6+7i^7+8i^8=5i-6-7i+8=2-2i 9i^9+10i^10+11i^11+12i^12=9i-10-11i+12=2-2i ................................................................................... ..................................