求几道职高数学题,在线等 职高数学题
\u4e00\u9053\u804c\u9ad8\u6570\u5b66\u9898\uff0c\u6c42\u5927\u795e\u5e2e\u5fd9\uff01\u5b83\u5728\uff080\uff0c+\u221e\uff09\u4e0a\u662f\u5355\u8c03\u9012\u51cf\u3002
\u56e0\u4e3af\uff08x\uff09\u662f\u5076\u51fd\u6570\uff0c\u6240\u4ee5f\uff08-x\uff09=f\uff08x\uff09
\u5728\uff080\uff0c+\u221e\uff09\u4e0a\u4efb\u53d6x1\u548cx2\uff0c\u4e14x1\u5c0f\u4e8ex2\uff0c\u5219-x2\u5c0f\u4e8e-x1\u3002
\u7531\u4e8ef\uff08x\uff09\u5728\uff08-\u221e\uff0c0\uff09\u4e0a\u662f\u589e\u51fd\u6570\uff0c\u6240\u4ee5f\uff08-x2\uff09\u5c0f\u4e8ef\uff08-x1\uff09
f\uff08x1\uff09-f\uff08x2\uff09=f\uff08-x1\uff09-f\uff08-x2\uff09\u5927\u4e8e0
\u5373f\uff08x1\uff09-f\uff08x2\uff09\u5927\u4e8e0\uff0c\u5373f\uff08x1\uff09\u5927\u4e8ef\uff08-x2\uff09\u6240\u4ee5\u5b83\u5728\uff080\uff0c+\u221e\uff09\u4e0a\u4e3a\u5355\u8c03\u9012\u51cf
当x=-1时取最小，为-11
2.由A点作高d垂直于a，设交点为D，取BD=k
角c为60度，可得到d=√3 CD=1〉BD=2〉c=√7
角B=arcsin√3/√7
由A点做垂线AH，设交点为H
则可以得到CH=1，AH=√3〉BH=1
角B为arctg√3=60度
1 x=-1时 最小值为-11
2 c^2=a^2+b^2-2*a*b*余弦的60度
=>c=7的根号
1.最小值为13
2.用余旋定理做，可是公式我早忘了~~~
-_-|||
y=4x^2+8x-7
=4(x^2+2x-7/4）
最小值11
问题太烂
1,6
2,c=2.646 A=79 B=41
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