The demand function of a monopolist is given by $p = 1500- 2x- x^2$, then value of marginal revenue when x = 20 is :

220

The correct answer is Option (1) → 220

The demand function,

$P(x)=1500-2x-x^2$

Total revenue = $P×x=(1500-2x-x^2)x$

$=1500x-2x^2-x^3$

$MR=\frac{d(TR)}{dx}=1500-4x-3x^2$

Substituting $x=20$,

$MR=1500-4(20)-3(20)^2$

$=220$