若f(x)=asin(x+TT/4)+3sin(x-TT/4) 是偶函数,则a=

若f(x)=asin(x+TT/4)+3sin(x-TT/4) 是偶函数,则a=
若f(x)=asin(x+TT/4)+3sin(x-TT/4) 是偶函数,则a=

若f(x)=asin(x+TT/4)+3sin(x-TT/4) 是偶函数,则a=
X=TT/4时式子为asin(TT/2)
X=-TT/4时式子为3sin(-TT/2)=-3sin(TT/2)
二者相等
所以答案-3