一道高中函数题,高人来帮忙啊!~~~ 一道高中数学题，各路高人帮帮忙啊~谢谢O(∩_∩)O~\(≧...
\u9ad8\u4e2d\u4e00\u9053\u51fd\u6570\u9898\uff0c\u5404\u8def\u9ad8\u4eba\u5e2e\u5e2e\u5fd9\u554a\uff0c3Q~f(x)-x\u6070\u6709\u4e09\u4e2a\u4e0d\u540c\u7684\u96f6\u70b9\u5c31\u662fy\uff1df(x)\u4e0ey\uff1dx\u6709\u4e09\u4e2a\u4ea4\u70b9
x^2+4x+2\u4e0ey\uff1dx\u4ea4\u4e8e\uff08\uff0d2\uff0c\uff0d2\uff09\uff08\uff0d1\uff0c\uff0d1\uff09
y\uff1d2\u4e0e\u3000y\uff1dx\u4ea4\u4e8e\u4ea4\u4e8e\uff082\uff0c2\uff09
\u7531\u56fe\u50cf\u53ef\u77e5
\u4e8c\u6b21\u51fd\u6570\u503c\u57df\u4e3a [0\uff0c+\u221e\uff09\uff0c\u8bf4\u660e a > 0 \uff0c\u4e14\u5224\u522b\u5f0f = (-4)^2 - 4ac = 0 \uff0c
\u6240\u4ee5 ac = 4 \uff0ca > 0 \uff0cc > 0 \u3002
\u56e0\u4e3a f(1) = a-4+c \u2264 4 \uff0c\u56e0\u6b64 a+c \u2264 8 \uff0c
\u7531\u5747\u503c\u5b9a\u7406\u77e5 a+c \u2265 2\u221a(ac) = 4 \uff0c\u56e0\u6b64 4 \u2264 a+c \u2264 8 \uff0c
u \u53ef\u5316\u4e3a (a+c)/4 - 2/(a+c) \u662f a+c \u7684\u589e\u51fd\u6570\uff0c
\u56e0\u6b64 a+c = 4 \u65f6 u = 1/2 \uff0ca+c = 8 \u65f6 u = 7/4 \uff0c
\u6240\u4ee5 1/2 \u2264 u \u2264 7/4 \u3002
就是他们是反函数，就有
y=f(x)=lnx
f(2x)=ln2x=lnx+ln2(x>0)
y=e*的图像与y=f(x)的图像关与y=x对称可知
y=f(x)=lnx,f(2x)=ln2x
怎么会f(2x)=lnx=ln2?不可能吧.除非x=1
第二个说法是对的
y=e*的图像与y=f(x)的图像关与y=x对称可知
y=f(x)=lnx,f(2x)=ln2x=lnx+ln2(x>0)
绛旓細鎶涚墿绾縴=a(x+1)^2+c ABC鍏卞渾 A(4,0) C(-1,0)鍦嗗績鐐逛负(1.5,0) 鍗婂緞涓2.5 (x-1.5)^2+y^2=2.5^2 浠ｅ叆x=0 y=卤2 鍙杫=2 B(0,2)A B浠ｅ叆鎶涚墿绾縴=a(x+1)^2+c 0=a(4+1)^2+c 2=a(0+1)^2+c 0=25a+c 2=a+c a=-1/12 c=25/12 y=-(x+1)^2...
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绛旓細In(x)+In(2x+1)=In[x(2x+1)]=0 鍗充腑鎷彿鍐厁(2x+1)=1 寰2x^2+x-1=0 鍙В寰梮=-1鎴杧=1/2 浣嗗洜涓簒澶т簬0锛屽師寮忎腑In(x)鎵嶆湁鎰忎箟锛屾墍浠ヨ垗鍘粁=-1 鎵浠ョ粨鏋滀负x=1/2
绛旓細y=e*鐨勫浘鍍忎笌y=f(x)鐨勫浘鍍忓叧涓巠=x瀵圭О 灏辨槸浠栦滑鏄弽鍑芥暟锛灏辨湁 y=f(x)=lnx f(2x)=ln2x=lnx+ln2(x>0)
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