Answer: The first option.
Step-by-step explanation:
1. To solve this exercise you need to remember that:
- An even function is a function with the following property:
f(-x)=f(x)
- An odd function is a function with this property:
f(-x)=-f(x)
2. By definition, the contangent is an odd function, therefore you have that:
cot(-θ)=-cot(θ)
Then:

3. So, you can coclude that the first step is wrong. Therefore, the answer is the first option.
I believe the answer is D.
(x, y ) = (- 6, 3 )
Since both equations express y in terms of x, we can equate them
2x + 15 = -
x + 1
( add
x to both sides )
x + 15 = 1 ( subtract 15 from both sides )
x = - 14
( multiply both sides by 3 and divide by 7 )
x = ( 3 × - 14 )/7 = - 6
substitute x = - 6 into either of the 2 equations for y- coordinate )
y = ( 2 × - 6 ) + 15 = 3
solution : (x, y ) = ( - 6, 3 )