Which of these represents the arc length of f(x)f(x)f(x) on [a,b][a, b][a,b]?
∫ab1+[f′(x)]2dx\int_{a}^{b} \sqrt{1 + [f'(x)]^2} dx∫ab1+[f′(x)]2dx
∫ab(1+[f′(x)]2)dx\int_{a}^{b} (1 + [f'(x)]^2) dx∫ab(1+[f′(x)]2)dx
π∫ab[f(x)]2dx\pi \int_{a}^{b} [f(x)]^2 dxπ∫ab[f(x)]2dx
∫ab1+f(x)dx\int_{a}^{b} \sqrt{1 + f(x)} dx∫ab1+f(x)dx