# Using Binomial Theorm to compute f

• November 1st 2012, 10:18 AM
flametag3
Using Binomial Theorm to compute f
Hey, I was hoping someone could check and tell me if I have done the below question correctly
The question asks that we use Binomial theorm and compute $(2- i)^5$

The answer I get is ( $-38 -119i$). I for some reason think it is incorrect, could someone double check for me please and thank you!
• November 1st 2012, 10:41 AM
wasp
Re: Using Binomial Theorm to compute f
Quote:

Originally Posted by flametag3
Hey, I was hoping someone could check and tell me if I have done the below question correctly
The question asks that we use Binomial theorm and compute $(2- i)^5$

The answer I get is ( $-38 -119i$). I for some reason think it is incorrect, could someone double check for me please and thank you!

Yep. It's off.

$(2 - i)^5 = 2^5 - 5*2^4*i + 10*2^3*I^2 - 10*2^2*i^3 + 5*2*i^4 - i^5$

$=~(32-80+10) + (-80+40-1)i$

Does this help?

-Dan