f(x)=x平方+4ax+2a=6,最后6前面的“=“应该是“+"吧.
f(x)=x^2+4ax+2a+6=(x+2a)^2+2a+6-4a^2>=2a+6-4a^2,
(1)由f(x)的值域为[0,inf),知:2a+6-4a^2=0
得a=1.5或a=-1,
(2)由题意“函数f(x)大于等于零恒成立”知2a+6-4a^2>=0,即(2a-3)*(a+1)
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f(x)=x平方+4ax+2a=6,最后6前面的“=“应该是“+"吧.
f(x)=x^2+4ax+2a+6=(x+2a)^2+2a+6-4a^2>=2a+6-4a^2,
(1)由f(x)的值域为[0,inf),知:2a+6-4a^2=0
得a=1.5或a=-1,
(2)由题意“函数f(x)大于等于零恒成立”知2a+6-4a^2>=0,即(2a-3)*(a+1)