Question

已知a,b为实数,且ab=3,a+b=4,

Answer 1

(a+1)(b+1)=ab+(a+b)+1=8

(a-1)(b-1)=ab-(a+b)+1=0,得到a=1,b=3或者a=3,b=1

(a-1)/(a+1)=(a-1)(b+1)/(a+1)(b+1)=(a-1)(b+1)/8

同理(b-1）/（b+1）=(b-1)(a+1)/8

则（a-1）/（a+1）=0或者0.5