SOLUTION: please help me solve this. I don't know how to start. (3+10i)^2

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: please help me solve this. I don't know how to start. (3+10i)^2       Log On


   

Question 182634: please help me solve this.
I don't know how to start.
(3+10i)^2

Found 2 solutions by jim_thompson5910, Alan3354:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
%283%2B10i%29%5E2 Start with the given expression.


%283%2B10i%29%2A%283%2B10i%29 Expand. Remember, something like A%5E2=A%2AA


%283%29%283%29%2B%283%29%2810i%29%2B%2810i%29%283%29%2B%2810i%29%2810i%29 FOIL.


9%2B30i%2B30i%2B100i%5E2 Multiply.


9%2B30i%2B30i%2B100%28-1%29 Replace i%5E2 with -1. Note: i%5E2=-1.


9%2B30i%2B30i-100 Multiply.


-91%2B60i Combine like terms.


So %283%2B10i%29%5E2=-91%2B60i.

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
please help me solve this.
I don't know how to start.
(3+10i)^2
---------------
There's nothing to solve for. This can be expanded, tho
(3+10i)^2 = (3+10i)*(3+10i)
= 3*(3+10i) + 10i*(3+10i)
= 9+30i + 30i -100
= -91 + 60i Bigger numbers, but it is simpler.