Answer:
28. C
29. D
30. C
Explanation:
28.From the graph you can see that the height i.e f(x) was only increasing from 200 to 300 of x and 100 to 150 of f(x) and then continue to decrease. therefore we can then say f(x) is increasing when x is greater than or equal to 200 and when x is less than or equal to 300 i.e option C.
29. at x=500 f(x)=0
therefore at x= 500 f(x) was at it minimum