Problem: If x,y and 2x+2y​ are not zero, then (2x+2y​)−1[(2x)−1+(2y​)−1] equals
Answer Choices:
A. 1
B. xy−1
C. x−1y
D. (xy)−1
E. none of these
Solution:
(2x+2y​)−1[(2x)−1+(2y​)−1]=2x+2y​1​(2x1​+y/21​)
=2x+2y​1​xy(2y​+2x)​=xy1​=(xy)−1.