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caroash09
Jul 2, 2009, 08:10 PM
x-intercepts for the following polynomial function:

f(x)=x²+x-1



my ans. Is coming -1+√5/2 something... help me

Perito
Jul 2, 2009, 08:34 PM
0 = x^2 + x -1

Using the quadratic formula:

x = \frac {-1 \pm \sqrt {1+4}}{2}

x = \frac {-1 \pm \sqrt {5}}{2}

So, one root is x = \frac {-1 + \sqrt {5}}{2}

and the other is x = \frac {-1 - \sqrt {5}}{2}