Integral

class Integral1(Scene):
    def construct(self):

        integral = Integral("f(x) \: dx", "a", "b")
        self.add(integral)

        integral.a.set_color(RED)
        integral.b.set_color(BLUE)

        integral.symbol.set_color(WHITE)
        integral.function.set_color(WHITE)

Fundemental Theorem

class FundementalTheorem(Scene):
    def construct(self):

        a = MathTex("0", color=GREEN)
        b = MathTex("\pi", color=GREEN)

        integral = Integral("\cos(x) \: dx", a, b)

        tex = MathTex(integral)
        self.add(tex).wait(1)


        tex.terms = [
            integral,
            "=",
            [ Function("\sin", b), "-", Function("\sin", a) ]
        ]

        self.play(TransformInStages.progress(tex))