Check Answers Please?

Question

1. 5+(2+3i) + (-3-7i)
= 4 + -4i

2. (5-10i) - (2+i)
= 7 - 9i

3. -5i(2-3i)
= -10i - 15

4. (2+3i)(-3-7i)
= (1)(4i)

Answer 1

I Made a Mistake Problem #4 Answer Is
21-20i

Answer 2

Nope. I'd be interested in how you got your answers.

1. 5+(2+3i) + (-3-7i) = (5+2-3) + (3-7)i = 6 - 4i

2. (5-10i) - (2+i) = (5-2) + (-10-1)i = 3 - 11i

3. correct, but in standard form is -15 - 10i

4. (2+3i)(-3-7i) = -6 - 14i - 9i - 21i^2 = -6 - 23i + 21 = 15 - 23i

Answer 3

I went back and I corrected problem 2 and 3.
In problem 2 I found my mistake, But in problems 1 and 4 I'm stuck and can't figure out how you got those answers.
I did the problems at least 4 times already and I keep getting the same answers:/

Answer 4

I think i know what i did wrong in problem 4!
My multiplication is wrong!

Answer 5

Ouch! I blew it in #1. You are correct. Dunno how I got 6.

Answer 6

Lol:D
You were being speeding threw the problems just like me!
i did that in problem 4!
I got the right answer now!
Thank you!

Answer 7

Sorry "being" shouldn't have been there.
Another mistake!