Evaluate $\iint_{R}e^{-x-y}dx dxy$ 

Evaluate $\iint_{R}e^{-x-y}dx dxy$, where $R$ is the region in the first quadrant in which $x+y \leq 1.$


Answers can be viewed only if
  1. The questioner was satisfied and accepted the answer, or
  2. The answer was disputed, but the judge evaluated it as 100% correct.
View the answer
Erdos Erdos
The answer is accepted.
Join Matchmaticians Affiliate Marketing Program to earn up to 50% commission on every question your affiliated users ask or answer.