Continuing from his method.
Year 10 method. You will learn Calculus in Year 11 and find a more efficient method. For now this method will do.
Finding intercepts
and
intercepts.
I like
better than
. So we will find the
intercept first.
intercept: Let
Now,
Let
Plot this into your graph. Your graph should now look like this.
Now you have a dilemma. Where should you start your graph? There are two possible starting points. Top of the
axis or the bottom of the
axis. So how do we decide?
If we look at our equation of our graph,
If we expand it out, we get
. Since the power of three is the highest power, we will inspect the coefficient of it. It is
. Two is a positive number. So we will start from the top.
It will start here!
Now, we will consider three possible drawings.
SMOOTH LINE![ONE DEGREE]
BOUNCE OFF (REJECTION!)[EVEN DEGREE]
HORIZONTAL INFLEXION (JINK/HUMP) [ODD DEGREE]
So let's consider the first intercept it will cross. Our closest one is 1. We can see that,
was our graph.
Let's focus on
. It has a degree of 1. So it will be a smooth line forward.
Our next
intercept is 0. Let's focus on
. It has a degree of 1. So it will also be a smooth line.
So your graph is now like this.
Finally the
intercept is -2. Let's focus on
. It has a degree of 1. So it will also be a smooth line.
So your graph is like this.