Question

The number of plants in a terrarium is given by the function P(c) = -1.2c2 + 4c + 12 where c is the number of mg of plant food added to the terrarium. The amount of plant food that produces the highest number of plants is _____ mg (round to the nearest hundredth).

Answer 1

15.33mg

Explanation:

Given the number of plants in a terrarium is given by the function

P(c) = -1.2c^2 + 4c + 12

At the hihest number of plants produced, dP(c)/dc = 0

dP(c)/dc = --2.4c + 4

0 = -2.4c + 4

2.4c = 4

c = 4/2.4

c = 1.67

To get the highest number of plant produced, we will substitute c = 1.67 into the original function

P(c) = -1.2c^2 + 4c + 12

P(1.67) = -1.2(1.67)^2 + 4(1.67) + 12

P(1.67) = -3.34668 + 18.68

P(1.67) = 15.33332

Hence the amount of plant food that produces the highest number of plants is 15.33mg (round to the nearest hundredth).