Which polynomial is a difference of two squares?

x^2 − 12

x^2 + 12

x^2 − 36

x^2 + 36

Question

Which polynomial is a difference of two squares? 

 x^2 − 12 

 x^2 + 12 

 x^2 − 36 

 x^2 + 36

anonymous · Answer

difference -- so we're looking for subtraction
two squares -- so both terms must be squares; the first is a square in all cases ($x^2$) but what about our second terms? which of the options are even differences?

anonymous · Answer

b and d

anonymous · Answer

well, (b) and (d) are only *sums* -- not differences. so (a) and (c) are our candidates; look at their second terms, i.e. $12,36$; which of those is a perfect square? :)

anonymous · Answer

36?