1) 1-2*3^x>0
2x+1>0
x不存在
2）sinX+cosX=-√2
sinXcosπ/4+cosXsinπ/4=-1
sin(X+π/4)=-1
X=2kπ-3π/4
2tanX=2tan(2kπ-3π/4)=2tanπ/4=2
3）f(x)=loga[(x-a/2)^2+(3a-a^2/4)]
a>1,x≥a/2,a/2≤2,f(x)在区间[2,＋∞)上是增函数
∴1