Answer:
B
Step-by-step explanation:
sorry if its wrong
Answer:
The Answer is B 8+ 6=14
Step-by-step explanation:
14-8=6
8+6=14
14-6=8
I got

What we know
cos a=-3/5.
sin b=12/13
Angle A interval are between 180 and 270 or third quadrant
Angle B quadrant is between 90 and 180 or second quadrant.
What we need to find
Cos(b)
Cos(a)
What we are going to apply
Sum and Difference Formulas
Basics Sine and Cosines Identies.
1. Let write out the cos(a-b) formula.

2. Use the interval it gave us.
According to the given, Angle B must between in second quadrant.
Since sin is opposite/hypotenuse and we are given a sin b=12/13. We. are going to set up an equation using the pythagorean theorem.
.




so our adjacent side is 5.
Cosine is adjacent/hypotenuse so our cos b=5/13.
Using the interval it gave us, Angle a must be in the third quadrant. Since cos is adjacent/hypotenuse and we are given cos a=-3/5. We are going to set up an equation using pythagorean theorem,
.




so our opposite side is 4. sin =Opposite/Hypotenuse so our sin a =4/5.Sin is negative in the third quadrant so
sin a =-4/5.
Now use cosine difference formula



Hope this helps
We need to simplify

First lets factor


=


by applying the radical rule
![\sqrt[n]{ab} = \sqrt[n]{a} \sqrt[n]{b}](https://tex.z-dn.net/?f=%20%5Csqrt%5Bn%5D%7Bab%7D%20%3D%20%20%5Csqrt%5Bn%5D%7Ba%7D%20%5Csqrt%5Bn%5D%7Bb%7D%20)

By applying the radical rule
![\sqrt[n]{x^m} = x^{m/n}](https://tex.z-dn.net/?f=%20%5Csqrt%5Bn%5D%7Bx%5Em%7D%20%3D%20x%5E%7Bm%2Fn%7D)
So

=

=

Now let's factor

By applying the radical rule
![\sqrt[n]{ab} = \sqrt[n]{a} \sqrt[n]{b}](https://tex.z-dn.net/?f=%20%5Csqrt%5Bn%5D%7Bab%7D%20%3D%20%20%5Csqrt%5Bn%5D%7Ba%7D%20%20%5Csqrt%5Bn%5D%7Bb%7D%20)
,

So

=

So

=

We know that
![\sqrt[n]{x} = x^{1/n}](https://tex.z-dn.net/?f=%20%5Csqrt%5Bn%5D%7Bx%7D%20%3D%20x%5E%7B1%2Fn%7D)
so

We now have
We know that
So

We now got

We can notice that the numerator and the denominator both got √2 in a multiplication, so we can simplify them, and we get:

All in All, we get

=

Hope this helps! :D
You get discontinuity when in this function you divide by 0. You will divide by 0 if x+4 = 0. That means that x = -4
y value for this example doesn't matter because for x = -4 you will have discontinuity. Since the only answer that has -4 as x value is D, that has to be solution.
Answer is D