求y=log2 X+logx (2X)的值域

问题描述:

求y=log2 X+logx (2X)的值域

y=log2X+logx(2X)
=log2X+logx2+logxX
=log2X+logx2+1
显而易见,x的取值范围为{x|01时
log2X>0
y=log2X+logx2+1
=log2X+1/(log2X)+1
>=2+1=3
(2)当0