Posted by **latesha** on Saturday, December 17, 2011 at 8:33pm.

Use factoring by grouping to solve the following equation.

4x3 + 8x2 − 9x − 18 = 0

x = 1 (smallest value)

x = 2

x = 3 (largest value)

- math -
**drwls**, Sunday, December 18, 2011 at 8:21am
x = 1 is not a solution. You can easily prove that yourself.

When x = 2,

4x^3 + 8x^2 − 9x − 18 = 28

So that is not a solution, either. Neither is x = 3. How did you come up with your answers?

When x = -2,

-32 +32 +18 -18 = 0

So x+2 is a factor of the polynomial.

The other factor is

(4x^3 + 8x^2 − 9x − 18)/(x+2)

= (4x^2 -9) = (2x +3)(2x-3)

So the other two solutions are

x = 3/2 and x = -3/2

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