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

1 Answer
Oct 5, 2016

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

Explanation:

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 term.

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

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