GWD-30-19

anf

thanks!

yoyo0327

分子分母同时乘以√(n+1) +√n

考的是化简

anf

still don't get it, can someone explain more on this question >.<

jiangta

x^2-y^2=(x+y)(x-y)

orangecat

Q19:

If n is positive, which of the following is equal to 1 / {√(n+1) -√n}?

 

A.          1

B.          √(2n+1)

C.          √(n+1) / √n

D.         √(n+1) - √n

E.          √(n+1) + √n

这道题想考什么？怎么做？谢谢。