In what direction does the graph of $y = x^{2} - 8 x + 16$ $y = x^2 -8x + 16$ open?

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Answer 1 · 2016-10-05T19:09:14

Look at the sign of $a$ $a$ .
$+ a \to$ $+a rarr$ opens upwards and $- a \to$ $-a rarr$ opens downwards

If you have the equation of a parabola you can always tell which way it is open by looking at the sign of the $x^{2}$ $x^2$ term.

If $a > 0$ $a > 0$ (ie positive,) then there is a minimum turning point, the parabola is the 'right way up' and opens upwards.

If $x < 0$ $x <0$ (ie negative,) then there is a maximum turning point, parabola is "upside down and opens downwards.

In what direction does the graph of y = x^2 -8x + 16y=x2−8x+16y = x^2 -8x + 16 open?