The easy WitCH below comes courtesy of the Evil Mathologer. It is a worked example from Cambridge’s *Essential Mathematics Year 9* (2019), in a section introducing parabolic graphs.

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# Witch 14: Stretching the Truth

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3 Replies to “Witch 14: Stretching the Truth”

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*Essential Mathematics Year 9* (2019), in a section introducing parabolic graphs.

There is no quadratic function which can have a vertex and axial intercepts where pictured.

If we ignore the x-intercepts, the graph has form y=a(x+3)^2 +5. Using (0,-5) gives a=-10/9

If, on the other hand we ignore the turning point the graph has form y=a(x+1)(x+5). Using (0,-5) gives a=-1.

Which is close, but not the same as -10/9.

Have I missed anything?

Yep, that’s it. It’s simply not a parabola.

It’s not even a picture of a parabola…