How do I find the roots of a quadratic equation?
A quadratic equation has the form ax2 + bx + c Our goal is to find values of x such that ax2 + bx + c = 0These values of x are known as the "roots" of the quadratic.
Exercise:Find the roots of x2 + 5x + 6
Let's try finding the roots by guessing. How about x=0?02 + 5.0 + 6 = 6If we plug this value of x into the expression, it will simplify to the value 6. This is not a root.
Let's try another. How about x=-2(-2)2 + 5.(-2) + 6= 4 - 10 + 6= 0
Great! We have found a root.
Trying many different values of x would take us a long time. Luckily there is a special equation we can use to find these roots easily called the "quadratic formula".
Whiteboard WorkWrite the quadratic equation on the board as seen on https://en.wikipedia.org/wiki/Quadratic_equationDraw parabolas and demonstrate intercepts with x-axis to show a visual representation of the exercise above.
