How do you solve #x^2-x-4=0# graphically?

1 Answer
Sep 4, 2016

Answer:

From the graph we get #x~~ -1.6 and x ~~2.6#
We cannot find the exact answer graphically.

Explanation:

First you need to draw the graph of the parabola as
#y = x^2 -x -4#

You can do this by plotting points.
Draw up a table, choose some x-values and work out the y-values.

If you compare #color(red)(y) = x^2 -x -4 # and # x^2 -x -4 = color(red)(0)#, you will see that the only difference is that #y=0#

#y=0# is the equation of the x-axis. The question is asking..

"Where does the parabola intersect the x-axis?"
OR
What are the x-intercepts for this graph?"
OR
Find the roots of the equation #0 = x^2 -x -4#

From the graph we get #x~~ -1.6 and x ~~2.6#
We cannot find the exact answer graphically.

graph{x^2-x-4 [-2.365, 2.635, -1.62, 0.88]}