I don't understand how to use the graph or number line method to solve a quadratic inequality. For example x^2-3>2x I found x=-1 and x=3 but I don't understand how to use the graph or number line.... Pls help me!!!
Many thanks :)
Many thanks :)
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So you graph the parabola, intersecting the x axis at -1 and 3 using a dotted line. Vertex is at (1, -4)
Now test a point inside the parabola. If the statement is true, shade the interior. If false, shade the exterior.
The part of the x-axis that is shaded is the solution.
ex: try (0, 0). That is false, so shade exterior
That means x > 3 or x < -1
Now test a point inside the parabola. If the statement is true, shade the interior. If false, shade the exterior.
The part of the x-axis that is shaded is the solution.
ex: try (0, 0). That is false, so shade exterior
That means x > 3 or x < -1
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kk go to http://www.wolframalpha.com/input/?i=+x%…
that is a plot of your inequality. the blue line is the parabola, duh, and the pink is the linear 2x function. notice on the graph where the shaded area is and compare to your coordinates x= -1 and x = 3
that is a plot of your inequality. the blue line is the parabola, duh, and the pink is the linear 2x function. notice on the graph where the shaded area is and compare to your coordinates x= -1 and x = 3
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http://www.bbc.co.uk/scotland/learning/bitesize/higher/maths/algebra/quadratic_theory2_rev5.shtml
this might help?
this might help?