18. If f(x)=[xsin πx] {where [x] denotes greatest integer function}, then f(x) is:
since x denotes the greatest integers which could the negative or the positive values, also x has a domain of all real numbers, and has no discontinuous point, then x is continuous in (-1,0).
Answer: B]
20. Given that g(x)=1/(x^2+x-1) and f(x)=1/(x-3), then to evaluate the discontinuous point in g(f(x)) we consider the denominator of g(x) and f(x). g(x) has no discontinuous point while f(x) is continuous at all points but x=3. Hence we shall say that g(f(x)) will also be discontinuous at x=3. Hence the answer is:
C] 3
21. Given that f(x)=[tan² x] where [.] is greatest integer function, from this we can see that tan x is continuous at all points apart from the point 180x+90, where x=0,1,2,3....
This implies that since some points are not continuous, then the limit does not exist.
Answer is:
A]
        
             
        
        
        
Answer:
1.Graphing the linear equations by constructing the table of values. 
2.Graphing the linear equation using the slope and y-intercept (i.e. y=mx+b)
3.Graphing the linear equation by connecting x-intercept and y-intercept.
Step-by-step explanation:

 
        
                    
             
        
        
        
Answer:
(4,-1) (4,0) (4,1)
Step-by-step explanation:
If you graph this, it will be a straight vertical line.  No matter what y is, x will always be 4.
 
        
             
        
        
        
, it is important to recognize that the point (x,y) in the first quadrant represents any
point on the semicircle. In Figure 2, the same semicircle is shown with the inscribed rectangle drawn for
three different values of x.
        
             
        
        
        
I believe the answer is 23/40 but I don’t have paper and pencil hope this helps