Completing The Square - Plotting Quadratics

Completing The Square - Plotting Quadratics | Algebra | Maths | FuseSchool

Completing the square is another way of solving quadratics (as well as by factorising and by using the quadratic formula). Completing the square will always work, whatever the quadratic (whereas factorising does not always work). Completing the square also helps us when sketching the graph, as it provides us with the coordinates of the turning point (minimum or maximum). In this video we look at how to plot the quadratic using completing the square. Completing the square quickly gives us the coordinates of the turning point (the minimum or maximum point), and if we solve it we get the coordinates of the points that the quadratic crosses the x-axis. The quadratic equation already gives us the y-intercept. So we have 4 points from which we can sketch the quadratic from. (x - a)2 + b = 0, where (a, b) are the coordinates of the minimum/maximum point.