The marginal revenue from selling $x$ units is $MR = 40 - 6x$ rupees. What is the total revenue function?

Explanation

1. 01

   $R(x) = \int (40 - 6x)\,dx = 40x - 3x^{2} + K$.

2. 02

   Selling nothing earns nothing, $R(0) = 0$, so $K = 0$.