Answers

2016-08-01T10:43:31+08:00
 Vertex. y = a(x – h)2 + k, where (h, k) is the vertex. in y = ax2 + bx + c (that is, both a's have exactly the same value). The sign on "a" tells you whether the quadratic opens up or opens down.
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thank you so much. can you give me an example?