Week 9-Graphing Quadratic Equations

This week we learned about graphing quadratic equations in factored form. In factored form, we can find the roots, as well as the axis of symmetry. With this information, we can draw a quick graph depicting what our parabola would look like.

ex. Graph the equation y=-2x^2-6x+20

graphing the equation with only the factored form won’t give us a complete parabola, but it will give us enough information to get a rough idea.



$latex y=-2(x+5)(x-2)

replace the “y” with 0.


rearranging the bracketed “x’s” will give us our roots


(x+5) -> x=-5, (x-2) -> x=2

with the x-intercepts, we know that when graphed will be in the format (x,y). But since the x-intercept is where the parabola crosses the x-axis, the y-intercept will equal 0. The x-intercepts will be (-5,0) and (2,0). The axis of symmetry is half way between both roots, so the AOS will be x=-1.5.

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