Question 320386
    In which direction does the parabola for the quadratic equation y = -5x2 – 16x + 21 open?
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To determine, always look at the "coefficient" associated with the {{{x^2}}} term.  
If it is POSITIVE (happy face:U), it opens upwards.
If it is NEGATIVE (sad face:n), it opens downwards.
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In your case, you're looking at:
{{{5x^2}}}
The coefficient is 5 which is POSITIVE.
So the parabola opens upwards.