## mikaa_toxica13 2 years ago Find the product: (3x + 4)(3x − 4) 9x^2 + 24x − 16 9x^2 + 16 9x − 16 9x^2 − 16

1. sjerman1

multiply it by foiling

2. mikaa_toxica13

okay well can u help

3. sjerman1

|dw:1363713172377:dw|

4. sjerman1

just foiling out

5. sjerman1

does this make sense @mikaa_toxica13

6. mikaa_toxica13

uhm there is no 9x^2 - 12 answer. only a 9x^2 - 16

7. sjerman1

sorry 4*-4 = -16

8. mikaa_toxica13

oh okay thank u. can u help with a few others ?

9. sjerman1

sure no problem

10. sjerman1

sorry im doing a few things at once, and at work right now so if it takes me a min to respond, dont worry

11. mikaa_toxica13

Factor Completely: x^2 + 25 (x + 5)(x + 5) (x + 5)(x − 5) (x − 5)(x − 5) Prime

12. mikaa_toxica13

ok :)

13. sjerman1

so the easiest way to do this is to multiply out the factors you have there you know that it needs to multiply out to a positive 25

14. mikaa_toxica13

okay. i think its B.

15. sjerman1

now also have you go over the list of items that are prime?

16. sjerman1

because if you multiply 5*-5 you get -25 not +25

17. mikaa_toxica13

oh

18. sjerman1

this factor is prime, im not sure if you were looking up or waiting for a responce but this one can not be factored

19. sjerman1

to justify this you can take the only one that will work, or rather come close, would be (x + 5)(x + 5) or (x − 5)(x − 5) and both of these would give you a middle term either -10x or +10x

20. mikaa_toxica13

i was trying to look it up :/ i jus cant really get it

21. sjerman1

for this, i know its going to be annoying for now, it will be a lot easier the more you do this, but multiply out the terms to find out what it comes out to

22. sjerman1

(x + 5)(x + 5) = x^2+10x+25 (x + 5)(x − 5) = x^2-25 (x − 5)(x − 5) = x^2-10x+25

23. sjerman1

then you can see, oh none of these match the answer, therefore it's prime.

24. mikaa_toxica13

oh okay thanks ! Factor Completely: 36x^2 − 25 (6x − 5)(x + 5) (6x + 5)(6x + 5) (6x − 5)(6x − 5) <--- answer (6x + 5)(6x − 5) Factor Completely: 3x^2 − 21 3(x^2 − 7) <---- answer 3(x + 7)(x − 7) 3(x + 7)(x − 3) Prime

25. sjerman1

welllllll. on the first one, the easy thing to look at tis you need to have a -25 so what multiplies to give you a -25

26. mikaa_toxica13

nmv, to teh first one, the answer is D

27. sjerman1

good job!

28. sjerman1

on the second one, very good job!

29. mikaa_toxica13

Factor Completely: 2x^2 − 32 Prime<--- answer 2(x^2 − 16) 2(x + 4)(x + 4) 2(x + 4)(x − 4)

30. sjerman1

this one is not prime.

31. mikaa_toxica13

Factor Completely: x2 − 36 (x + 6)(x − 6) (x + 6)(x + 6) (x − 6)(x − 6)<---answer Prime

32. mikaa_toxica13

okay then its gotta be B

33. sjerman1

Factor Completely: 2x^2 − 32 Prime 2(x^2 − 16) 2(x + 4)(x + 4) 2(x + 4)(x − 4)<--------answer, because 2(x^2-16) -> 2(x+4)(x-4)

34. sjerman1

Factor Completely: x2 − 36 (x + 6)(x − 6)<---answer (x + 6)(x + 6) (x − 6)(x − 6) Prime

35. sjerman1

keep in mind that 6*-6 gives you -36

36. sjerman1

but the easiest way to look at this is x2 − 36, there is no middle term, this means there has to be one factor is that x + something and x - something to make the middle term go away

37. sjerman1

does this make sense @mikaa_toxica13

38. mikaa_toxica13

yes. thank u soo much !

39. sjerman1

good!

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