Expand (x - 2y)4.

A: x4 + 8x3y + 24x2y2 + 32xy3 + 16y4

B: x4 - 8x3y + 24x2y2 - 32xy3 + 16y4

C: x4 - 8x3y + 24x2y2 - 34xy3 + 16y4

D: x4 - 8x3y + 28x2y2 - 32xy3 + 16y4

Question

Expand (x - 2y)4.

A: x4 + 8x3y + 24x2y2 + 32xy3 + 16y4
		
B: x4 - 8x3y + 24x2y2 - 32xy3 + 16y4
		
C: x4 - 8x3y + 24x2y2 - 34xy3 + 16y4
		
D: x4 - 8x3y + 28x2y2 - 32xy3 + 16y4

anonymous · Answer

aren't they all the same?

anonymous · Answer

not really.

anonymous · Answer

i think its x^4 - 8x^3y + 24x^2y^2 - 32xy^3 + 16y^4 (B)

amistre64 · Answer

they only differ in sign changes

anonymous · Answer

@amistre64 actually that and the coefficients.

amistre64 · Answer

...28 and 34 .... sneaky

anonymous · Answer

the numbers are different too. the numbers, signs and all that. they're not the same. none of them.

amistre64 · Answer

1   4       6     4    1  pascal row
  x    x      x      x    1   power down
  1 -2y  -2y  -2y -2y   power up
-------------------

anonymous · Answer

x^4 - 8x^3y + 24x^2y^2 - 32xy^3 + 16y^4??

amistre64 · Answer

http://www.wolframalpha.com/input/?i=expand+%28x+-+2y%29%5E4 but yeah, B is good