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## teenandtoddlermom 2 years ago need help (x^3+y^2)(x^3-y^2) can someone help me figure this out and explain?

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1. satellite73

you have to do four multiplications

2. teenandtoddlermom

I need to multiply

3. satellite73

$x^3\times x^3$ is the first one

4. teenandtoddlermom

x^6? do I add the exponents?

5. satellite73

then $$x^3\times (-y^2)$$

6. satellite73

yes

7. satellite73

then $$x^3\times y^2$$

8. satellite73

and finally $$y^2\times (-y)^2$$

9. teenandtoddlermom

x^6-y^4?

10. satellite73

you will notice that middle terms add up to zero, so you are only left with $x^6-y^4$

11. satellite73

yes

12. satellite73

it is always true that $$(a+b)(a-b)=a^2-b^2$$

13. teenandtoddlermom

see, all I need is confidence and your great guidings! :) I might make it after all. LOL

14. jim_thompson5910

you can also use a table to help you multiply |dw:1362367881354:dw|

15. teenandtoddlermom

Hi Jim. thank you, that helps as well. :)

16. jim_thompson5910

each cell is the result of multiplying the corresponding row and column headers so the upper left cell is the result of multiplying the two x^3 terms the upper right cell is the result of multiplying x^3 and y^2 etc etc giving you this |dw:1362367968379:dw|

17. jim_thompson5910

then you add up all the terms and combine like terms if you can to get x^6 - y^4 (the x^3y^2 terms will cancel as you got before)

18. teenandtoddlermom

great explanation. I need all the tips I can get. thank you! :)

19. jim_thompson5910

you're welcome

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