Answer:
Step-by-step explanation:
A. (x, y) is not an equation.
B. 2 + 7 = 9 Not a linear equation, as there is no variable.
C. 3x + 5 = 20 This is a linear equation.
D. y = 2x + 1 This is a linear equation.
Answer:
The last one
Step-by-step explanation:
Your question seems a bit incomplete, but for starters you can write

Expanding where necessary, recalling that

, you have

and you can stop there, or continue to rewrite in terms of the reciprocal functions,

Now, since

, the final form could also take

or
The distance would be 3 units because the difference between 2 and 5 is 3.