Question 119261: I solved the quadratic equation of 3x^2+11x-20=0 by factoring and have the correct answer of x=4/3, -5. How would I solve graphically by creating a tchart with 6 points that will lie on the parabola. Finding the vertex will be helpful. The graphical work must be sufficient to determine the solutions without knowing them from algebraic work. Any help you can give would be greatly appreciated.
Answer by Fombitz(32388)   (Show Source):
You can put this solution on YOUR website! Typically, I start at x=0 and move up by 1.
0 -20
1 -6
2 14
3 40
4 72
5 110
6 154
I see there is a zero between x=1 and x=2.
Then go back the other direction.
-1 -28
-2 -30
-3 -26
-4 -16
-5 0
The second zero is easy to find at x=-5.
You can then go from x=1 to x=2 in increments of 0.1 to get more detail.
1.0 -6.0
1.1 -4.3
1.2 -2.5
1.3 -0.6
1.4 1.3
Now between x=1.3 and x=1.4.
Again, keep getting finer and finer.
1.31 -0.4
1.32 -0.3
1.33 -0.1
1.34 0.1
Now between x=1.33 and x=1.34.
You can keep going...
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