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October 25, 2016
Posted by **julez** on Saturday, October 29, 2011 at 7:07pm.

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

- college algebra -
**Damon**, Saturday, October 29, 2011 at 7:20pmlet z = x^2

then

z^2 + 3 z - 4 = 0

(z-4)(z+1) = 0

z = 4 or z = 1

so

x^2 = 4 or x^2 = 1

so

+/- 2 and +/- 1