## anonymous 5 years ago find the product for (5+3i)(5-3i)... I got 24-9a. Does anyone know if this is correct?

1. anonymous

Should be 25-9i. You use foil if you've ever been taught that.

2. anonymous

3. anonymous

yeah, that's what I used.. and since the 9i was squared i added a -1. must have calculated it our wrong. Thanks

4. anonymous

yeah, do the i's cancel out? So it would be 25-9?

5. anonymous

And actually should be adding. Let's start over lol.

6. anonymous

ha good call!

7. anonymous

25-9i^2. That is what you should get, which can be simplified.

8. anonymous

ok so I can add the 2 and the 25?

9. anonymous

Ok. So i represents an imaginary number, it's what you get when you take the square root of a negative number. And the ^ is raised to a power. So we have 25-9i^2. So if $i=\sqrt{-1}$ then $i^2=-1$ So we get 25-9(-1)

10. anonymous

someone help me

11. anonymous

ok so would that be the answer? or can I simplify from there? Since there aren't any i's do I need to add those all to get one number?

12. anonymous

Yes to more simplifying. 25-9(-1) is the same as 25+9=34

13. anonymous

oh so the answer should be just 34?

14. anonymous

Yep.

15. anonymous

Thanksabunch

16. anonymous

No problem. :)

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