Which of the following integrals represents the area of the surface obtained by rotating the curve y=eˣ, 1 1) ∫(2 to 1) 2πeˣ dx
2) ∫(1 to 2) 2πeˣ dx
3) ∫(1 to 2) 2πx eˣ dx
4) ∫(2 to 1) 2πx eˣ dx