Edexcel A Level Maths: Pure:复习笔记2.2.1 Quadratic Graphs
Quadratic Graphs
What are quadratic graphs?
- The general equation of a quadratic graph is
- Their shape is called a parabola ("U" shape)
- Positive quadratics have a value of
so the parabola is upright
- Negative quadratics have a value of
so the parabola is upside down 
Using quadratic graphs
You need to be able to:
- sketch a quadratic graph given an equation or information about the graph
- determine, from the equation, the axes intercepts
- factorise, if possible, to find the roots of the quadratic function
- find the coordinates of the turning point (maximum or minimum)
You may have to rearrange the equation before you can find some of these things
Exam Tip
- Your calculator may tell you the roots of a quadratic function and the coordinates of the turning point
- But don't rely on it – think about how many marks the question is worth and how much method/working you should show
- Remember sometimes you'll need to rearrange an equation into the form
Worked Example
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