And so we can sketch out what the graph of y is equal to f of x is going to look like. Then repeat using two equations and eliminate the same variable you eliminated in 4. Take two equations at a time and eliminate one variable c works well 5.
The next example shows how we can use the Vertex Method to find our quadratic function. Most "text book" math is the wrong way round - it gives you the function first and asks you to plug values into that function. There you have it.
The righthand side is going to be nine.
The coordinates of the vertex. We'll assume the axis of the given parabola is vertical. The best way to learn this stuff is to do it yourself.
The graph contains three points and a parabola that goes through all three. And this form of a function, this is actually called vertex form because it's very easy to pick out the vertex. So, here, to solve x squared, plus six x, plus eight is equal to zero, it will be useful to factor this.