If #P(x)=3x^3-2x^2-x+8#, what is #P(-3i)#?

1 Answer
smendyka
Jul 20, 2017

See a solution process below:

Explanation:

For each occurrence of #color(red)(x)# in #P(x)# substituting #color(red)(-3i)#

#P(color(red)(x)) = 2color(red)(x)^3 - 2color(red)(x)^2 - color(red)(x) + 8# becomes:

#P(color(red)(-3i)) = 2color(red)((-3i))^3 - 2color(red)((-3i))^2 - color(red)(-3i) + 8#

#P(color(red)(-3i)) = 2color(red)((-27i^3)) - 2color(red)((9i^2)) + 3i + 8#

#P(color(red)(-3i)) = -54i^3 - 18i^2 + 3i + 8#

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