math extra credit?

Question

If a = 2 + i, then in the form a + bi, what does a^-1 equal? In this problem i represents the imaginary number square root of -1.

Answer 1

This is the answer:


1/(2+i) = (2-i)/{(2-i)*(2+i)}

(2-i)/(4-i^2) = (2-i)/5

2/5 - i/5

Answer 2

Given: a=2+i
a^-1=(2+i)^-1
=1/(2+i)
Multiply by (2-i)/(2-i):

a^-1=(2-i)/(2+i)(2-i)
=(2-i)/(4-i^2)
=(2-i)/(4-(-1^-1/2)(-1^1/2)
=(2-i)/4-(-1)
=(2-i)/(4+1)
=(2-i)/5
=2/5-i/5
=2/5+(-1/5i)

Answer 3

Extra credit? I don't think so. I'm not doing any more of your homework and I would advise everyone else not to help you either. You neither appreciate help nor accept critisism.

DO YOUR OWN HOMEWORK.

Then you can just go ahead and report me. They already know about you.

Answer 4

1/(2+i)

(2-i)/(2-i) * 1/(2+i)

(2-i)/(4-i^2)

(2+i)/5

2/5 + i/5

Answer 5

Clarify ....
What do you mean with "then in the form a + bi" ?
For a correct answer |i need that info.

Answer 6

http://www.coolmath.com/

http://www.aplusmath.com/