Question

函数f（x）=x+ 4 +3在（负无穷大,-2]上,

Answer 1

因为函数f(x)=x+a/x（a>0)在（-∞,-根号a]是增函数,在(-根号a,0)是减函数,所以f(x)=x+4/x+3当x=-2时有最大值,最大值=-2+4/(-2)+3=-1