Answer:
15 . Undefined
16. undefined
Step-by-step explanation:
I think it’s d I’m not sure though
Primeiro multiplica o -2 com tudo que tem dentro do parenteses (chuveirinho) -114 = -5x -2(4x+18)
-2 . 4x = -8x + -2 . 18 = -36 = -8x-36
Agora soma os números com incógnitas (no caso x)
-114 = - 5x - 8x -36
Joga a incógnita do outro, tornando positiva
-114 = -13x - 36
13x -114 = -36
e o 114 do outro lado, ficando positiva também
13x -114 = -36
13x = - 36 + 114
13x = 78
x = 78 /13
x= 6
ESPERO TER AJUDADO :)

is a complex number that satisfies
![\begin{cases}r\cos x=-3\\[1ex]r\sin x=4\\[1ex]r=\sqrt{(-3)^2+4^2}\end{cases}](https://tex.z-dn.net/?f=%5Cbegin%7Bcases%7Dr%5Ccos%20x%3D-3%5C%5C%5B1ex%5Dr%5Csin%20x%3D4%5C%5C%5B1ex%5Dr%3D%5Csqrt%7B%28-3%29%5E2%2B4%5E2%7D%5Cend%7Bcases%7D)
The last equation immediately tells you that

.
So you have
![\begin{cases}\cos x=-\dfrac35\\[1ex]\sin x=\dfrac45\end{cases}](https://tex.z-dn.net/?f=%5Cbegin%7Bcases%7D%5Ccos%20x%3D-%5Cdfrac35%5C%5C%5B1ex%5D%5Csin%20x%3D%5Cdfrac45%5Cend%7Bcases%7D)
Dividing the second equation by the first, you end up with

Because the argument's cosine is negative and its sine is positive, you know that

. This is important to know because it's only the case that

whenever

. The inverse doesn't exist otherwise.
However, you can restrict the domain of the tangent function so that an inverse can be defined. By shifting the argument of tangent by

, we have

All this to say

So,

.