Answer:
(a)Therefore the value of x=
(b) Therefore the value of x 
Step-by-step explanation:
Horizontal tangent line: The first order derivative of a function gives the slope of the tangent of the function. The slope of horizontal line is zero.If the slope of tangent line is zero then the tangent line is called horizontal tangent line.
(a)
Given function is,

Differential with respect to x

For horizontal tangent line, f'(x)=0
3+ 3 cos x= 0
⇒3 cos x=-3
⇒cos x=-1
⇒x = 180° 
Therefore the value of x=
(b)
Given that, the slope is 3.
Then,f'(x)=3
3+ 3 cos x= 3
⇒3 cos x= 3-3
⇒cos x=0
⇒x = 90° 
Therefore the value of x 
 
        
             
        
        
        
B.) would be correct
(x,y)
x=-5
y=x+4
y=(-5)+4
y=-1
(-5,-1)
        
             
        
        
        
Answer:
See below. 
Step-by-step explanation:
13. D
Simply subtract. 85376 - 37793 = 47583.
14. C
[Something] - 32497 = 26348
Add 32497 to both sides: 
[Something] - 32497 + 32497 = 26438 + 32497
[Something] = 58845
15. C
Compute each difference: 
A: 51455 - 26478 = 24977
B: 49351 - 15274 = 34077
C: 63286 - 37439 = 25847
(D: 46307 - 21550 = 24757)
16. B
Simply subtract: 
143864 - 112955 = 30909
17. A
First, find the difference: 
85732 - 39864 = 45868
Only 45798 (A) is less than 45868. 
(Note that B is equal to, not less than). 
18. C
Subtract: 
45932 - 29574 = 16358. 
19. B
Subtract: 
96834 - 31727 = 65107 - 12156 = 52951
20. C
27301 - 12352 - [Something] = 7356
14949 - [Something] = 7356
Add [Something] to each side: 
14949 = 7356 + [Something]
Subtract 7356 from each side. 
7593 = [Something]
Note: Do you need help with subtraction specifically? These questions can be solved with simply with a calculator, but perhaps that is not the intention here. Anyways, I recommend using Khan Academy to improve your arithmetic skills if necesary. 
 
        
             
        
        
        
Answer:
It is the one on the right
Step-by-step explanation:
 
        
                    
             
        
        
        
Left 3 because the 3 is in the parenthesis