Mathematics 4 ESO – Unit 7 ELEMENTARY FUNCTIONS page 76 activity 6
a) Watch the video on “Building a Quadratic Function” and answer:
- I) What variable is represented by the letter “x”? And by the letter “y”?
- II) How do we initially recognise the quadratic function?
- III) The general form of the quadratic function is y = ax2 + bx + c What are the values of the variables “a”, “b” and “c” in this example?
- IV) Why is the graph symmetrical?
- What is the “vertex”? Where is it?
- What three ways can we use to represent quadratic functions?
b) Watch the video on “Quick Way of Graphing a Quadratic Function in Standard Form” and answer:
I) For the function y = –3x2 + 12x + 4
- i) Find the axis of symmetry and draw it in a graph.
- ii) Find the vertex and draw it.
- iii) Find the values of y for: x=1 ; x=–1 ; x=2 and x=–2
- iv) Draw the function.
II) Graph these functions:
- i) 3x2 + 12x + 1
- ii) x2 + x + 4
- iii) –x2 – 5x + 7
- vi) 2x2 – 6x – 1