f(x)=(x+a)(bx+2a)=bx^2+abx+2ax+2a^2=bx^2+(ab+2a)x+2a^2因为f(x)为偶函数,所以ab+2a=0a(b+2)=0a=0或b=-21)a=0时,f(x)=bx^2,它的值域不可能为(-∞,4],所以a≠02)b=-2时,f(x)=-2x^2+2a^2,x=0时,其最大值为2a^2,因为...