设公比为q,第二项为a,则有四项分别为a/q ,a ,aq ,aq^2.列方程组：a^4.q^2=1 (1) a + aq =-3/2 (2)解之得：a=-2 ,q=-1/4 或者a=1/2 ,q=-4,将答案代入四项可得：a/q=8 ,a=-2 ,aq=1/2 ,aq^2=-1/8 ,或者反顺序：a/q=-1/8...