SOLUTION: Plot the graph of y= x3- 1.5x2- 8.5x +4.5 from x= -4 to x= +4 at 1 unit intervals, and use the graph to solve the cubic equation x³-1.5x2 -8.5x + 4.5= 0

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Question 189342: Plot the graph of y= x3- 1.5x2- 8.5x +4.5 from x= -4 to x= +4 at 1 unit intervals, and use the graph to solve the cubic equation x³-1.5x2 -8.5x + 4.5= 0
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
Plot the graph of y= x3- 1.5x2- 8.5x +4.5 from x= -4 to x= +4 at 1 unit intervals, and use the graph to solve the equation x³-1.5x2 -8.5x + 4.5= 0
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I did that. I use the graphing software from www.padowan.dk.com/graph/ (it's free)
I suspected that 0.5 is a zero because of the fractions in the equation, and it is.
Multiply the eqn by 2, then, after dividing by (x-1) you have
2x^2 - x - 18 = 0
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation (in our case ) has the following solutons:



For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=145 is greater than zero. That means that there are two solutions: .




Quadratic expression can be factored:

Again, the answer is: 3.26039864469807, -2.76039864469807. Here's your graph:
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