(1)
f(x)=log<2>(x+1) +√(1-x)
x+1 >0 and 1-x≥0
x>-1 and x≤1
-1
(2)
y=√log<0.5>(3x-6)
3x-6>1
3x>7
x>7/3
定义域=(7/3, +∞)
(3)
y=(a-3)^x
lny = xln(a-3)
(1/y)y' = ln(a-3)
y' =ln(a-3) .(a-3)^x
y' <0
ln(a-3) .(a-3)^x <0
0<(a-3)<1
-3a的取值范围是 : -3
(4)
1≤log<2>x<2
2^1≤x<2^2
2≤x<4