If $C(x)= ax^2 -bx - c$ represents the total cost function then the slope of the tangent to the marginal cost curve at the point (x, y ) is :

2a

The correct answer is Option (2) → 2a

The total cost function is,

$c(x)=ax^2+bx-c$

and, Marginal cost is,

$mc(x)=\frac{dc(x)}{dx}$

$=2ax-b$

and,

Slope of the tangent = $\frac{d(mc(x))}{dx}=2a$