# Math Help - Calculate intervals - cost and revenue function

1. ## Calculate intervals - cost and revenue function

Cost and revenue function, calculate the intervals where the profit is increasing?

C(x) = 0.32x^2 - 0.00004x^3
R(x) = 0.848x^2 - 0.0002x^3

Im lost!!

2. ## Re: Calculate intervals - cost and revenue function

the profit function is the difference between cost and revenue, so

$P(x) = (0.848 - 0.32)x^2 + (-0.0002--0.00004)x^3$
simplify terms in brackets...
$P(x) = 0.528x^2 -0.00016x^3$

now can you use the methods you have been taught to find the values of x where P(x) is increasing?