1/(√2+√1)=√2-√1
1/(√3+√2)=√3-√2
1/(√4+√3)=√4-√3
1/(√5+√4)=√5-√4
(1/(√2+√1)+1/(√3+√2)+1/(√4+√3)+...+1/(√2012+√2011) )×(√2012+1)
=(√2012 - √1) (√2012+1)
= 2012 -1
=2011(√2012 - √1) (√2012+1)= 2012 -1=2011这步怎么算啊(1/(√2+√1)+1/(√3+√2)+1/(√4+√3)+...+1/(√2012+√2011) )×(√2012+1)=[(√2-√1)+(√3-√2)+..+(√2012-√2011)] (√2012+1)=(√2012 - √1) (√2012+1)=2012-1( (a+b)(a-b) =a^2-b^2 )=2011点P(-a²-1,|b|+2)一定在第几象限-a²-1<0|b|+2 >0点P(-a²-1,|b|+2)一定在第2象限