We're neither concave upwards nor concave downwards here.

Concave upwards.

That's where we went from going concave upwards to concave downwards.

We're concave downwards.

You're concave downwards.

We're concave downwards.

We're concave upwards.

Before that, we're concave upwards, and then after that we're concave downwards.

You could even imagine, this concave upwards that we measured, that's this, concave upwards, and then this concave upwards is that.

It has to go from being negative in a concave downward to positive in concave upwards, or it has to go from positive in concave upwards to negative in concave downwards.

And then we're concave.

We were concave upwards.

We'll be concave downwards.

We are upwards, concave upwards.

We know it's concave upwards.

Concave upwards looks like this.

That's why it's called concave upwards.

From 0 to 2 3, we are concave downwards, and then at 2 3, we become concave upwards.

And then we're concave upwards around 0, until we get, we're concave upwards as long as x is greater than minus 3, and then at minus 3 we become concave downwards again.

Because we're concave upwards all around 0.

That's what we said was concave upwards.

And what does concave upwards look like?

So that means it's concave upwards there.

And and why is this concave upwards?

I said that concave upwards is when you're like a U, concave downwards is when you're like an upside down U.

Now, let's look at the concave downward scenario.

In concave upwards, it increases the whole time.

That's what concave upwards just tells us, right?

Now, in concave downwards, the slope is decreasing.

We're concave downwards over this interval right here.

So you have concave, and you have convex.

So, for example, this is a concave quadrilateral

Now we actually want it to be concave downwards because concave downwards looks like that, that means you found a maximum point.

The second derivative is positive tells us that we are concave upwards, really over this whole combined area function, we're concave upwards.

Now, over what interval of this function's domain, maybe I'll call it h of x, is this curve concave upwards or concave downwards?

We're concave upwards, until x is equal to 3.

This concave downwards right here, that's this, right here.

Concave downwards, you could probably guess what it looks

You know what today's leadership is doing? Concave length.

Hopefully, you understand visually what concave upwards and concave downwards means, and an inflection point, but what does this mean for the second derivative?

And this concave downwards, right here sorry, I meant to do it in the red color this concave downwards right here, is this, right there.

And the way I remember concave quadrilaterals, or really concave polygons of any number of shapes is that it looks like something has caved in.

When the second derivative is negative, you're concave this way.

And if the second derivative is positive, it's concave upwards.

And if the second derivative is negative, it's concave downwards.