æå°å¼ä¸º8
m=(3x+y-5)/(x-1)+(x+3y-7)/(y-2)
=(3x+x^2-1-5)/(x-1)+(x+3x^2-3-7)/(x^2-1-2)
=(x^2+3x-6)/(x-1)+(3x^2+x-10)/(x^2-3)
m'(x)=(2x+3)/(x-1)-(x^2+3x-6)/(x-1)^2+(6x+1)/(x^2-3)-(6x^3+2x^2-20x)/(x^2-3)^2
=(x^2-2x+3)[1/(x-1)^2-1/(x^2-3)^2]
=(x^2-2x+3)(x^2+x-4)(x^2-x-2)/[(x-1)^2*(x^2-3)^2]
å 为x>â3,å æ¤åªæx^2-x-2çå¼å¯è½ä¸º0
令mâ(x)=0,åï¼x^2-x-2=0,解å¾ï¼x=2ï¼x=-1ä¸ç¬¦åèå»ï¼
æ以ï¼
å½â3å½x>=2æ¶,m'(x)>=0,m(x)æ¯å¢å½æ°.
æ以ï¼å½x=2æ¶,måå¾æå°å¼ä¸º8
æx=2代å
¥æç©çº¿æ¹ç¨y=x^2-1å¾y=3
æ以ç¹Påæ 为(2,3).
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