The amount of revenue a company makes per day by selling x items is given by the function f(x) = 14x - 0.2x2. How many items should be sold if the company wants to maximize their profit?

30 items
35 items
70 items
40 items

Question

The amount of revenue a company makes per day by selling x items is given by the function f(x) = 14x - 0.2x2. How many items should be sold if the company wants to maximize their profit? 

       30 items
       35 items
       70 items
       40 items

anonymous · Answer

Can you put that in vertex form?

anonymous · Answer

i don't know

anonymous · Answer

Complete the square to get it in that form

anonymous · Answer

i'm not sure how to do that

anonymous · Answer

rearrange it to -1/5x^2+14x

Factor out the -1/5. what do you get?

anonymous · Answer

i'm sorry i don't know how to do that either

anonymous · Answer

Divide everything by -1/5