An extraordinarily quick way to sketch quadratics

Students in an algebra class spend many a week learning to sketch graphs of
quadratic functions:

y = ax2 + bx + c

And students are usually taught to memorise the following:

The graph is an upward or downward U-shaped graph (called a parabola)
depending on whether the leading coefficient a is positive or negative.

And the vertex of the parabola occurs at:   x = – (b/2a)

Plugging in this value of x into gives the y-coordinate of the vertex and plugging in other values of x will help ascertain the correct “steepness” of the U-shape.

My first piece of advice: FORGET THE FORMULA FOR THE VERTEX!  

Memorising is joyless!

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An extraordinarily quick way to sketch quadratics

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