Question

Find the product: (2x-4y)(2x+4y)

F=2x*2x=4x^2
O= 2x*4y=8xy
I= -4Y*2X=-8YX
L= -4y *4y= -16y^2
4x^2 +8xy -8yx -16y^2
4x^2-16y^2

Is this right?

Answer 1

yeah thats correct...

Answer 2

Thank you. Is it ok to turn the 8yx to 8xy, or is it fine the way it is?

Answer 3

\[4x^2-16y^2\] is correct.
8yx=8xy due to the communicative law for multiplication. So yes technically you can change it but generally it is fine to assume that the values are equal.

Answer 4

ok thank you

Answer 5

its easier to keep track of, for me, if you simply multiply it out.

2x -4y
2x +4y
---------
4x^2 -8x
+8x -16y^2
----------------
4x^2 - 16y^2

Answer 6

thank you, this does make it look easier, but I am assuming you couldn't use it on the longer ones.

Answer 7

you can use it on any of them ... distribution is just multiplication

Answer 8

that parts that dont "add together" just remain as seperate terms in the end

Answer 9

for example: (8x^4 +2x^2 -x +3) (x^2 +4)

8x^4 +2x^2 -x +3
x^2 +4
------------------
8x^6 +2x^4 -x^3 +3x^2
32x^4 +8x^2 -4x +12
--------------------------------
8x^6 +34x^4 -x^3 +11x^2 -4x +12