数学题(函数)俺的弱项啊!
\u5173\u4e8e\u51fd\u6570\u7684\u6570\u5b66\u9898\u2235f (x)\u662f\u5b9a\u4e49\u5728R\u4e0a\u7684\u5076\u51fd\u6570\uff0c\u4e14\u5f53X\u22650\u65f6\uff0cf(x)\u662f\u5355\u8c03\u51fd\u6570\uff0c
\u2234x=(x+3)/(x+4)\uff0c\u6216 -x=(x+3)/(x+4)\uff0c
\u5373x²+3x-3=0\uff0c\u6216x²+5x+3=0\uff0c
\u7531\u6839\u4e0e\u7cfb\u6570\u7684\u5173\u7cfb\u53ef\u77e5\uff0c
x²+3x-3=0\uff0c\u548cx²+5x+3=0\u7684\u6240\u6709\u7684\u6839\u4e4b\u548c= \uff08-3\uff09+\uff08-5\uff09= -8.
\u56e0\u4e3a\u5f53x=-1\u65f6\uff0cf\uff08x\uff09\u53d6\u6781\u503c\u3002\u5219\u5728x=-1\u5904\uff0cf\u2032\uff08x\uff09=0
f\u2032\uff08x\uff09=3ax²+2bx+c\uff0c\u4ee3\u5165f\u2032\uff08-1\uff09\uff1d3a-2b+c=0\u2026\u2026\uff081\uff09
\u4ee3\u5165f\uff081\uff09=a+b+c=-11\u2026\u2026\uff082\uff09
f\uff08-1\uff09=-a+b-c=5\u2026\u2026\uff083\uff09
\u89e3\uff081\uff09\uff082\uff09\uff083\uff09\u5f97\uff1a
a=1 b=\uff0d3 c=\uff0d9
\u8fd9\u6837f\uff08x\uff09=x³-3x²-9x
f\u2032\uff08x\uff09=3x²-6x-9
\u5728f\uff08x\uff09\u53d6\u6781\u503c\u7684\u5730\u65b9\uff0cf\u2032\uff08x\uff09=0\uff0c\u53733x²-6x-9=0
\u89e3\u5f97\uff1ax1=\uff0d1\u6216x2=3
\u4ee3\u5165f\uff083\uff09=27-3*9-27=\uff0d27
\u2235\u5f53x\uff1c-1\u65f6\uff0cf\u2032\uff08x\uff09\u5927\u4e8e0\uff0c\u6545f\uff08x\uff09\u5728\uff08\uff0d\u221e\uff0c\uff0d1\uff09\u9012\u589e\uff08\u53ef\u5728\u8fd9\u4e2a\u533a\u95f4\u5185\u4efb\u610f\u4ee3\u5165\u4e00\u4e2a\u6570\u5b57\u5f97\u5230\uff09
\u5f53-1\uff1cx\uff1c3\u65f6\uff0cf\u2032\uff08x\uff09\uff1c0\uff0c\u6545f\uff08x\uff09\u5728\uff08-1,3\uff09\u9012\u51cf
\u5f53x\uff1e3\u65f6\uff0cf\u2032\uff08x\uff09\uff1e0\uff0c\u6545f\uff08x\uff09\u5728\uff083\uff0c\uff0b\u221e\uff09\u9012\u589e
\u8fd9\u6837\uff0c\u2235x=-1\u5904\u4e8e\u4e00\u4e2a\u5148\u9012\u589e\u540e\u9012\u51cf\u533a\u95f4\uff0c\u6545x=-1\u5904\uff0cf\uff08x\uff09\u53d6\u6781\u5927\u503c\uff0cf\uff08-1\uff09=5
x=3\u5904\u4e8e\u4e00\u4e2a\u5148\u9012\u51cf\u540e\u9012\u589e\u533a\u95f4\uff0c\u6545x=3\u5904\uff0cf\uff08x\uff09\u53d6\u6781\u5c0f\u503c\uff0cf\uff083\uff09=\uff0d27
f\uff08x\uff09\u7684\u5355\u8c03\u9012\u51cf\u533a\u95f4\u4e3a\uff1a\uff08-1,3\uff09
f\uff08x\uff09\u7684\u5355\u8c03\u9012\u589e\u533a\u95f4\u4e3a\uff1a\uff08\uff0d\u221e\uff0c\uff0d1\uff09\u222a\uff083\uff0c\uff0b\u221e\uff09
y=2(t-0.5)^2+1
所以y的最大值在t=-1时取到,为4
y的最小值在t=0.5时取到,为1
高一数学 成才之路 上的一道选择题与其类似，看看吧！
绛旓細鎹㈠厓浠=sinx\2(-1<t>1)y=2(t-0.5)^2+1 鎵浠鐨勬渶澶у煎湪t=-1鏃跺彇鍒,涓4 y鐨勬渶灏忓煎湪t=0.5鏃跺彇鍒,涓1
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