Difference two square roots.

Possible method: Use the ``conjugate expression'', i.e. the expression with the middle sign reversed.

- Take
, and compute its limit at
. We have:

thus this is an undeterminate case. We multiply and divide bythe conjugate expression:

The numerator is constant and the denomainator has an infinite limit at , thus

- Take
. Here too we have an undeterminate case; we use the same method as above.

We transformed an undeterminate case into another one: both numerator and denominator have an infinite limit at . We use now a variant of te method exposed in subsection subsection limit polynomial and rational.

thus

Noah Dana-Picard 2007-12-28