Đáp án:
`A=(1+sqrta)/(a+1):(1/(sqrta-1)-(2sqrta)/(asqrta+sqrta-a-1))`
`=(sqrta+1)/(a+1):(1/(sqrta-1)-(2sqrta)/((a+1)(sqrta-1)))`
`=(sqrta+1)/(a+1):((a+1)/((a+1)(sqrta-1))-(2sqrta)/((a+1)(sqrta-1)))`
`=(sqrta+1)/(a+1):((a-2sqrta+1)/((a+1)(sqrta-1))`
`=(sqrta+1)/(a+1):(sqrta-1)^2/((a+1)(sqrta-1))`
`=(sqrta+1)/(a+1):(sqrta-1)/(a+1)`
`=(sqrta+1)/(a+1)*(a+1)/(sqrta-1)`
`=(sqrta+1)/(sqrta-1)`
`a=1995-2sqrt{1994}`
`a=1994-2sqrt{1994}+1`
`a=(sqrt{1994}-1)^2`
`=>sqrta=sqrt{1994}-1`
`=>A=(sqrt{1994}-1+1)/(sqrt{1994}-1-1)`
`A=sqrt{1994}/(sqrt{1994}-2)`
`A=(sqrt{1994}(sqrt{1994}+2))/(1994-4)`
`A=(1994+2sqrt{1994})/1990`
`A=(997+sqrt{1994})/995`