F(x) = ∫(a->g(x) f(t) φ(t) dtletf(t) φ(t) dt = dH(t)F(x) = ∫(a->g(x) f(t) φ(t) dt = H(g(x)) - H(a)F'(x) = g'(x) H'(g(x)) =g'(x) H'(g(x)) =g'(x) f(g(x)) φ(g(x))
下限带入为常数 求导后为零