## iwanttogotostanford one year ago ALGEBRA II HELP: Which of the following is the conjugate of 10 − 3i?

1. anonymous

change the sign in front of the imaginary part to find the conjugate

2. anonymous

(a + bi and (a - bi) are conjugates

3. anonymous

It would be 10+3i For example Conjugates: 3-2i, 3+2i

4. campbell_st

remember part of the general quadratic formula $-b \pm \sqrt{b^2 - 4ac}$ so if you think about $3 \pm \sqrt{-4} = 3 \pm 2i$ so the integer doesn't change its just the sign of the imaginary part

5. campbell_st

its also like the difference of 2 squares how do you get a 2 term quadratic (a -b)(a +b) = a^2 - b^2

6. iwanttogotostanford

sorry, my wi-fi went out for awhile @campbell_st @twistnflip @peachpi

7. iwanttogotostanford

so i would want to do the opposite for this one?

8. iwanttogotostanford

what is the first step?

9. anonymous

Yes the conjugates are easy. just switch the sign from positive to negative or vice versa. Here the conjugate is 10+3i

10. iwanttogotostanford

so it would be 13i?

11. iwanttogotostanford

wow I'm being stupid

12. anonymous

Nope do you have answer choices. It wouldn't be 13i because you can't add the two terms because one has a variable and the other does not lol

13. anonymous

14. iwanttogotostanford

i get it the question was just asking for the conjugate so its 10+3i

15. iwanttogotostanford

16. iwanttogotostanford

10 + 3i 10 − 3i 3 + 10i 3 − 10i

17. anonymous

a.

18. anonymous

Make sense?

19. iwanttogotostanford

thanks for helping me better understand, everyone!

20. iwanttogotostanford

yep, makes perfect sense