Question

Solve the equation 12x^3+x^2-9/2 x-1=0 given that -1/2 is a root

Answer 1

You must factor out (x-(-1/2)) from the equation. Does anyone know how to do this?

Answer 2

factor out a \((2x+1)\)

Answer 3

Or use Ruffini's rule. ( http://en.wikipedia.org/wiki/Ruffini's_rule)

Answer 4

Same thing different name:

http://mathworld.wolfram.com/SyntheticDivision.html
http://www.purplemath.com/modules/synthdiv.htm

Answer 5

-1/2 is a root => (2x+1) is a factor of 12x^3+x^2-9/2 x-1

12x^3+x^2-9/2 x-1 = (2x+1) (12x^2-5x-2) = (2x+1)(3x-2)(4x+1)
Put it =0, you can solve it!