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28 votes
28 votes
How can you tell whether a parabola is concave up (happy face) or concave down (sad face) by looking at the vertex form equation 

How can you tell whether a parabola is concave up (happy face) or concave down (sad-example-1
User Punchagan
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1 Answer

7 votes
7 votes
the sign of "a" tells you the direction of the parabola.
User Trafalmadorian
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