What is the area of the region enclosed by the curves y=lnx and y=ln^2x ? Solution First, we\'ll determine the limits of integration. These limits are represented by the intercepting points of the given curves. We\'ll equate: (ln x)^2 = ln x We\'ll subtract ln x: (ln x)^2 - ln x = 0 We\'ll factorize by ln x: ln x*(ln x - 1) = 0 We\'ll cancel each factor: ln x = 0 => x = e^0 = 1 ln x - 1 = 0 => ln x = 1 => x = e The intercepting points are (1 , 0) and (e , 1). The lower limit of integration is x = 0 and the upper limit of integration is x = e. To determine what curve is above of the other, we\'ll determine the monotony of the first derivative of the function f(x) = (ln x)^2 - ln x. f\'(x) = 2lnx/x - 1/x f\'(x) = (2ln x - 1)/x If x = 1 => f\'(1) = -1 If x = e => f\'(e) = 1/e The curve that is above is ln x and the area of the region is the definite integral of the function: ln x - (ln x)^2. Int [ln x - (ln x)^2]dx = Int ln x dx - Int (ln x)^2 dx We\'ll calculate Int ln x dx by parts: Int udv = uv - INt vdu Let u = ln x => du = dx/x Let dv = dx => v = x Int ln x dx = x*ln x - Int dx Int ln x dx = x*(ln x - 1) We\'ll apply Leibniz Newton to determine the definite integral: Int ln x dx = F(e) - F(1) F(e) = e*(ln e - 1) = e*(1-1) = 0 F(1) = -1 F(e) - F(1) = 1 We\'ll calculate Int (ln x)^2 dx by parts: Let u = (ln x)^2 => du = 2ln xdx/x Let dv = dx => v = x Int (ln x)^2dx = x*(ln x)^2 - Int 2ln xdx Int (ln x)^2dx = x*(ln x)^2 - 2*Int ln xdx But Int ln x dx = 1 Int (ln x)^2dx = x*(ln x)^2 - 2 We\'ll apply Leibniz Newton to determine the definite integral: F(e) - F(1) = e - 2 Int [ln x - (ln x)^2]dx = 1 - e + 2 Int [ln x - (ln x)^2]dx = 3 - e The area of the region bounded by the given curves is of (3 - e) square units..