How do you find the zeros of #g(x)=x^4-5x^2-36#?

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Answer 1 · 2016-11-01T02:01:14

#g(x) = x^4 - 5x^2 - 36# has 4 zeros, #x = -3, 3, -2i and 2i#

Given:

#g(x) = x^4 - 5x^2 - 36#

Let #u = x^2#

#g(u) = u^2 - 5u - 36 = 0#

#0 = u^2 - 5u - 36#

#0 = (u -9)(u + 4)#

#u = 9 and u = -4#

#x = +-3 and x = +-2i#

#g(x) = x^4 - 5x^2 - 36# has 4 zeros, #x = -3, 3, -2i and 2i#