Someone helps me, please.
(-8+4i)=(3+i)(-2+2i)
It is true, but how to get the right hand side from the left hand side?

Question

Someone helps me, please.
(-8+4i)=(3+i)(-2+2i)
It is true, but how to get the right hand side from the left hand side?

tkhunny · Answer

Essentially, you don't.  It is kind of a factoring exercise, but really requires that you know the end from the beginning.  Complex Numbers don't necessarily have unique factorizations.  Look up "Gaussian Primes".

You are asking, 12 = 3*4 -- How!!!  Really, 12 = 2*6 is just as good.  Or, 12 = 1*12.

It's only unique if it's prime.

mathmath333 · Answer

u can use "back solving".

anonymous · Answer

Don't get :) what is back solving?

mathmath333 · Answer

u need to convert solution to the question.

anonymous · Answer

It's kind of magic, like $-20-3\sqrt{13} =(1-\sqrt{13})(6+2\sqrt{13})$ 
There must exist some rule to get it.

anonymous · Answer

@mathstudent55

anonymous · Answer

@iambatman @iGreen @IrishBoy123

anonymous · Answer

I don't solve it, just want to know how to go to the right hand side quickly like that. :)

tkhunny · Answer

"back solve" means to get the LHS from the RHS, or what I described as "know the end from the beginning."  It's not necessarily unique.  Stop trying to make it unique.