(1)设年平均增长率是X
4%(1+X)^2=8%
X=0.414
(2)X2+3X+2=6
X2+3X-4=0
(X-1)(X+4)=0
X=1,X=-4
(3)设年平均增长率是X (1+X)^2=1+44% X=0.2
(4)