This is known as the summa symbol but for the sake of this video you just need to know This actually comes from Leibniz, one of the founders of calculus. Looking at Riemann sums, we'll get a better understanding of where this notation comes from. Now, in the future we're going to, especially once we start Under the curve of F of X, F of X and then DX. Lower bound at X equals A, so we'll write it there, we'll have our upper bound at X equals B, right over there. This area right over here would be the definite integral and so, we're gonna have our Of the definite integral and one of the powers Or as we'll see in the future, many of the boundariesĬould actually be curves but that's one of the powers We're not used to finding areas where one of the boundaries Is concern ourselves with the area under the graph, under the graph of Y is equal to F of X and above the X axis andīetween these two bounds, between X equals A and X equals B, so this area right over here and you can already get an appreciation. Going straight up like that and let's say that this is X equals B, just like that and what we want to do So, this is my Y axis, this is my X axis and let's say I have some function here, so this F of X right over there and let's say that this is X equals A and let me draw a line

So, let me draw a coordinate axes here, so that's my Y axis, this is my X axis, actually I'm gonna do two cases.

So, let me draw some functions here and we're actually gonna

The pillars of calculus and as we'll see, they're all related and we'll see that moreĪnd more in future videos and we'll also get a better appreciation for even where the notation of a definite integral comes from. Integrals and derivatives this is really one of Notion of a definite integral and with indefinite Gonna do in this video is introduce ourselves to the

Khan academy integral calculus