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问题: 数学题,在线等

若函数f(x)=(a-2)x^2+(a-1)x+3满足f(-x)=f(x),则函数f(x)的单调减区间是
要详细解释

解答:

f(x)=(a-2)x^2+(a-1)x+3满足f(-x)=f(x)
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=0
a=1
则函数为
f(x)=-x^2+3
则函数单调递减区间为[0,正无穷)