# 미분하고 그래프 그리기
>>> g <- function(x) {}
>>> body(g) <- D(body(f), 'x')
>>> curve(g, -5, 4, ylab = "g(x)")

# x2+1 적분하기
>>> f2 = function(x)(x^2 + 1)
>>> integrate(f2, lower = 0, upper = 1)
1.333333 with absolute error < 1.5e-14

# g 적분하기
>>> integrate(g, lower = 0, upper = 10)
1240 with absolute error < 1.4e-11
>>> f(10) - f(0)
1240