Answer:
The lines DE and BC have the same slope, therefore the two lines, DE and BC, are parallel
Step-by-step explanation:
To prove that DE is parallel to BC, we have;
The slope, m of the lines DE and BC are found from the following equation;

Where;
(x₁, y₁) and (x₂, y₂) = (b, c) and (a + b + c) for DE, we have;

Where we have (x₁, y₁) and (x₂, y₂) = (0, 0) and (2a, 0) for BC, we have;

Therefore, because the lines DE and BC have the same slope, the two lines DE and BC are parallel.
Subtracting the functions
2,0-1,-2-----(1,-2)
Answer:A rectangle that is not a square
Step-by-step explanation:
Answer:

Step-by-step explanation:
Method 1:
Arithmetic sequence is in the form

d is the common difference, can be found by:

Subtituting the
and 
You get:

Method 2 (Mathematical induction):
Assume it is in form 
Base step: 
Inducive hypophesis: 
GIven: 

Proved by mathematical induction
