For f(x) = a(x - h) squared + k, what does a size of a above 1 do to the graph?
- The graph becomes wider
- The graph shifts upward
- The graph becomes narrower
- The graph shifts sideways
Show answer and solution
Correct answer: C. The graph becomes narrower
1. The number a in front of the squared bracket controls a vertical stretch.
2. A size above 1 pulls every point further from the horizontal axis.
3. So the parabola looks narrower, while a size below 1 makes it look wider.
_Source: OpenStax Precalculus (CC BY 4.0), section 3.2 Quadratic Functions_