Question

Alex factored 32a^2 + 18b^2 using the following steps:
32a^2 + 18b^2 = 2(16a^2 + 9b^2)
= 2(4a + 3b)(4a - 3b)
Did he do it correctly? if not explain what he did wrong and how he can check his answers.

Answer 1

He didnt do it correctly...

32a^2 + 18b^2 = 2(16a^2 + 9b^2) = 2(4a + 3b)(4a - 3b)*WRONG*! He forgot the negative sign in front of 3b...

This is how he can check his answer

2(4a + 3b)(4a - 3b) = 2(16a^2-9b^2) = 32a^2-18b^2...which doesn't match the answer the answer they gave....

Answer 2

2(16a^2 + 9b^2) is correct but how did he get what goes next?

Answer 3

Sorry its taking so long to respond...Im also helping others.

Answer 4

One moment please.

Answer 5

Yes that is correct...But what he got next is wrong...He used A2 - B2 = (A + B)(A - B)

Answer 6

ok

Answer 7

its supposed to be (a + b) (a - b) ?

Answer 8

No thats what he used...And that was wrong..If you see when he times the +b and - b he should have had a -b^2 not a +b^2.

Answer 9

i sent u a PM... tell me if thats ok to put

Answer 10

Lol yeah I got it, Its good! lol :)

Answer 11

its impossible to factor out

Answer 12

to show why, take last 2(4a + 3b)(4a - 3b) and try to remove brackets by multiplying each of the terms which i hope you can do yourself?

Answer 13

@Tomas.A I already answered all her questions for this problem for her through messaging.

Answer 14

ah thats ok, but she still was asking for help in math chat, no idea why, so just confirmed what you said

Answer 15

Lol okay. :P Yeah I explained it and she got to the end, so I have no idea why. Thanks for letting me know! :)

Answer 16

so you done with her expanding, right?

Answer 17

Yes, I showed her everything and she even sent me a message making sure it was clear and correct...So she should be good. lol but I really dont know..You know how some people are just saying they get it when they dont and end up getting the answer without learning mostly anything. :P