need help in practice test (#44 ETS math subj. test booklet)
Posted: Wed Jul 23, 2008 11:01 am
Can someone help me with #44 in the ETS math subj practice test?
#44
if Z=e^(2*pi*i/5)
1+Z+Z^2+Z^3+5*Z^4+4*Z^5+4*Z^6+4*Z^7+4*Z^8+5*Z^9=?
the answer is -5e^(3*pi*i/5)
but I can't get it...hope someone here can help~ THx a lot~
#44
if Z=e^(2*pi*i/5)
1+Z+Z^2+Z^3+5*Z^4+4*Z^5+4*Z^6+4*Z^7+4*Z^8+5*Z^9=?
the answer is -5e^(3*pi*i/5)
but I can't get it...hope someone here can help~ THx a lot~