Question Video: Finding the 𝑦-Intercept Using a Graph of a Quadratic Function Mathematics

Video Transcript

Identify the 𝑦-intercepts of the quadratic function 𝑓 of 𝑥 equals 𝑥 squared minus one.

The quadratic 𝑓 of 𝑥 equals 𝑥 squared minus one is in the form 𝑓 of 𝑥 equals 𝑎𝑥 squared plus 𝑏𝑥 plus 𝑐. In this form, the 𝑦-intercept is located at the point zero, 𝑐. The coefficient of 𝑥 squared, 𝑎, equals one. The coefficient of the 𝑏-term would be equal to zero; we don’t have an 𝑥-term. And our 𝑐-value is equal to negative one. Using this method, we find a 𝑦-intercept at zero, negative one. Additionally, of course, we know that the 𝑦-intercept is the place that the graph crosses the 𝑦-axis. And if we look closely at this graph, that is halfway between zero and negative two, where 𝑦 equals negative one.