Quadratics - Role of the Discriminant Delta on Equation and Parabola & Exam Questions involving it

We learn about the role of the discriminant Delta, and how its sign determines the numbers of roots a quadratic has. We then work through 2 exam questions in which we'll need to find un unknown coefficient using our knowledge of what the sign / value of Delta has to be.
******* TIMESTAMPS / CHAPTERS *******
00:00 Introduction
00:32 Formula for Discriminant Delta
01:34 if Delta is Positive then the Quadratic has 2 distinct Real Roots
03:29 if Delta is Zero then the Quadratic has 1 Real Root
05:24 if Delta is Negative then the Quadratic has No Real Solution
06:40 Example 1, find k given the quadratic has two equal real roots
10:00 Example 2, find k if the quadratic has 2 distinct real roots and if it has no real root.