若函数f(x)=（a-2）x平方+（a-1）x+3是偶函数,请写出f（x）的单调区间.

f(x)=（a-2）x^2+（a-1）x+3是偶函数则f(-x)= (a-2)(-a)^2+(a-1)(-x)+3 =f(x) =（a-2）x^2+（a-1）x+3则(a-1)(-x)=(a-1)x则a-1=0a=1则函数为f(x)=-x^2+3则函数单调区间为-无穷,0)递增区间[0,正无穷)递减区间...