ACT Preparation / Unit 11 ACT 1015 short lesson, about 20 seconds
Vertex Form
Captions available
The idea
In vertex form, f(x) = a(x − h)² + k, the vertex is (h, k) and the axis of symmetry is x = h.
In practice
f(x) = 2(x + 1)² − 8 has vertex (−1, −8) and opens up. Expanded, it is 2x² + 4x − 6.
Where people slip
The sign inside flips: x + 1 means h = −1.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
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