9.解:(1)原式=42+1-3=14.
(2)原式=
=.
10.解:(1)[f(x) 2-[g(x) 2=(ax-a-x)2-(ax+a-x)2
=2ax·(-2a-x)=-4.
(2)∵f(x)·f(y)=4,∴(ax-a-x)(ay-a-y)=4.
∴ax+y+a-(x+y)-ax-y-ay-x=4,
即g(x+y)-g(x-y)=4.①
∵g(x)·g(y)=8,
∴(ax+a-x)·(ay+a-y)=8.
∴ax+y+a-(x+y)+ax-y+ay-x=8,
即g(x+y)+g(x-y)=8.②
由①②得g(x+y)=6,g(x-y)=2.∴=3.