已知函数f(x^2-3)=lgx^2/x^2-6
1个回答

(1)∵f(x²-3)=lgx²/(x²-6)

∴x²/(x²-6)>0,即x²>6,

令x²-3=t(t>3),则x²=t+3

∴f(t)=lg(t+3)/(t-3)

∴y=f(x)=lg(x+3)/(x-3)

∴y=f(x)表达式及定义域为:

y=f(x)=lg(x+3)/(x-3),x>3;

(2)y=f(x)是奇函数,证明如下:

f(-x)=lg(3-x)/(-x-3)

=lg(x-3)/(x+3)

=lg[(x+3)/(x-3)](-1次方)

=-lg(x+3)/(x-3)

=-f(x),

∴y=f(x)是奇函数.