[SOLVED] easy complex number questions

hi, could someone check the answers of these for me? btw, the book says that they are all wrong. i dont understand why.

1. If z = 2 + i, evaluate:

a) 3z = 6 + 3i

b)

2. Solve for z; expressing answers in the form a + ib

a)

b) Totally clueless about this one:

Solve for x.

3. Simplify:

I got 3i/2. but the answer is -3i/2. I dont get why.

Thanks

[SOLVED] solving complex number equation

Solve for z.

I tried it but nothing gets rid of the z.. could someone give me a hint? I multiplied by 2 + i on both sides, but that didn't work. did a whole lot of algebra bashing, but nothing gets rid of the 2z on the left hand side.

Quote:

Originally Posted by **mathaddict**

HI

Let

Multiply by its conjugate,

By comparing ,

.... 1

.... 2

Now solve the system for a and b

..