sososocool
幼苗
共回答了19个问题采纳率:84.2% 举报
1.∵a=1,x>1
∴f(x)=x²/(x-1)
=(x²-1+1)/(x-1)
=[(x+1)(x-1)+1]/(x-1)
=x+1+1/(x-1)
=x-1+1/(x-1)+2
≥2+2=4
等号仅当x-1=1/(x-1)时候成立,即x=2时.
又∵x=2>1
∴当x=2时,f(x)取得最小值4.
2.f(x)≥ax,(a∈R,x≠1)
ax²/(x-1)≥ax
(1)a=0,不等式化简得0≥0,恒成立,所以,x∈R且,x≠1
(2)a>0,①x=0,0≥0,成立.
②x>0,x/(x-1)≥1,解得,x>1
③x<0,x/(x-1)≤1,解得,x1
a
1年前
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