Question

This one is hard! If P(x)=5x^3+2x^2-x+1 find P(i)

Answer 1

plugging in i you get:
\[P(i) = 5i^{3}+2i^{2}-i+1\]
Now using the fact that:
\[i^{3} = -i, i^{2} = -1\]
we get:
\[5(-i)+2(-1)-i+1\]
simplifying we get out answer:
\[-1-6i\]

Answer 2

I will look at it and make sure it matches the teacher's answer

Answer 3

boy Joemath314159; not hard for you huh?

Answer 4

imaginary numbers are a mathematicians best friend >.> lolol

Answer 5

One quick question, how come the exponents get dropped?

Answer 6

and then just knowing how they work:
\[i^{1} = i, i^{2} = -1, i^{3} = -i, i^{4} = 1, i^{5} = i, \ldots \]
it repeats after that.

Answer 7

Wow. Thank you so much! I am glad you know it:) God bless u!