Simplify: √-16 • √-10?

Question

a. 4√10

b. -4√10

c. 4i√10 (I think its this one)

Simplify: 3(-6 + 8i) - (2 - 12) ( Im still lost but I believe its b)

a. -28 + 16i

b. -16 +16i

c -20 + 36i

these next two I am so lost:

Simplify: (4 - 2i) ²

a. 20 - 16i

b. 20

c. 12 - 16i

4 - 2i / 7 + 3i

a. 11 - 13i / 29

b. 11 - 14i / 29

c. 13 - 17i / 29

Answer 1

Nope.  the answer to 1. is -4sqrt10

Let's go step by step.  

sqrt(-16) = 4i

sqrt(-10) = isqrt(10)

(wish I had a radical symbol on my keypad like you do !)

Now, they want us to multiply these two factors, right ?

(4i)(i)(sqrt10) = 4(i^2)(sqrt10) = -4sqrt10

Do you see it ?

In problem 2, you typed the second term incorrectly.  You really mean:

-(2 - 12i), don't you ?

Then, just distribute 3, and collect like terms. The answer will be c.

For #3, do you know how to multiply binomials ?  Have you ever heard of FOIL ?

Does that help ?

Number 4 requires that you rationalize the expression.  Do you know what that means ?  Do you know what a conjugate of a complex number is ?  Use your text book, ask your teacher.

Good luck.

Answer 2

I hate being tricked into doing more than one question !!!

Question 1

√ ( 16 i ² ) • √ ( 10 i ² )

4 i • √10 i

- 4 √10

Question 2

Should question read as :-

3 (- 6 + 8 i) - (2 - 12 i) ????

- 20 + 36 i

Question 3

( 4 - 2 i ) (4 - 2 i )

16 - 16 i - 4

12 - 16 i

OPTION c

Question 4

( 4 - 2 i ) / ( 7 + 3 i )

(4 - 2 i ) (7 - 3 i)

-----------------------

(7 + 3 i) (7 - 3 i)

28 - 26 i - 6

---------------------

49 + 9

22 - 26 i

------------

58

11 - 13 i

---------------

29

OPTION a