## Announcements

WebWork:

• Quadratic Equations-Completing the Square – due Fri April 10 (Sec 2.2.3)
• Quadratic Equations-Zero Product – due Wed April 10 (Sec 2.2.1)
• Graphs-Graphs of Quadratic Equations – due Wed April 17

## Topics

We reviewed again our techniques for solving quadratic equations:

We then focused on applying the quadratic formula, with examples from the WebWork:

Another example from the Webwork–note that because the “discriminant” b^2 – 4ac < 0, we have “no real solutions” and instead have 2 complex solutions (but this WebWork exercises requires that you enter the solutions in terms of the square root of the negative number):

We then shifted to talking about graphs, in particular of “y = a linear expression” (straight lines) and “y = a quadratic expressions” (parabolas):

Review of equations and graphs of lines:

For quadratics, we started with the simplest such, y = x^2:

We discussed how the “roots” of a quadratic polynomial (the solutions of “ax^2 + bx + c = 0”) give the x-coordinates of the x-intercepts of the graph y = ax^2 + bx + c: