SOLUTION: I need help on multipying and taking "i" to powers. My question is: Evaluate the following epression for x=2i x^6 + 3x^3 - 4x^2 + 2x - 5 I used the dividing power rule

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: I need help on multipying and taking "i" to powers. My question is: Evaluate the following epression for x=2i x^6 + 3x^3 - 4x^2 + 2x - 5 I used the dividing power rule       Log On


   



Question 58739: I need help on multipying and taking "i" to powers.
My question is:
Evaluate the following epression for x=2i
x^6 + 3x^3 - 4x^2 + 2x - 5
I used the dividing power rule on one of the worked problems. The answer I got was -7 from this equation:
2(-1) + 3(2)(-i) - 4(2)(-1) + 2(i) - 5
-2 + 6(-i) + 8 + 2i - 5
1 + 8
1 + 8(-1)(1)
1 - 8

Answer by funmath(2933) About Me  (Show Source):
You can put this solution on YOUR website!
I need help on multipying and taking "i" to powers.
i^0=1
i^1=i
i^2=-1
i^3=-i
Whenever the powers are bigger than 3, divide the power by 4, whatever the remainder is tells you what you have:
i^4=1 ( because 4/4=1 r=0 and i^0=1)
i^13=i (because 13/4=3 r=1 and i^1=i)
i^102=-1 (because 102/4=25 r=2 and i^2=-1)
:
Evaluate the following epression for x=2i
:
x^6 + 3x^3 - 4x^2 + 2x - 5
(2i)^6+3(2i)^3-4(2i)^2+2(2i)-5
64(-1)+3(8)(-i)-4(4)(-1)+4i-5
-64-24i+16+4i-5
-53-20i
Happy Calculating!!!