Answer:
Step-by-step explanation:
Given that A is a square matrix and A is idempotent

Consider I-A
i) 
It follows that I-A is also idempotent
ii) Consider the matrix 2A-I

So it follows that 2A-I matrix is its own inverse.
Answer: Convenience sample.
Step-by-step explanation:
Convenience sample is also known as grab or accident or opportunity samples. It is a example of non probability sample that involves selecting of subjects because of the proximity, convenience and accessibility a researcher as to them. This type of samples are not reliable for data gathering when it involves a very large sample space, let's say a global audience.
2+a / 2 = 4 and b+6 /2 = 10
2+a=8. and. b+6 = 20
a=6. and. b=14
(a,b) , the other endpoint, is thus (6,14)
Answer:
20 3/20 rounds to 20
Step-by-step explanation:
The simplest possible form would be 8/13 which can be found by dividing by 10