Question

Which of the following represents a difference of squares binomial?
(k - 3)^2
k^4 - 81
k^4 + 81
(k^2 - 9)^2

Answer 1

A difference of two squares binomial can be written in one of two forms:
\[(a+b)(a-b)\]or\[a^2-b^2\]Which of your options is in one of these forms?

Answer 2

the last one

Answer 3

It's the second one : $$ k^4 - 81 = (k^2)^2 - 9^2$$

Answer 4

I can see why you went for the last one, since it's almost a difference of two squares. The issue is that the whole thing is squared again, so instead of \[a^2-b^2\]you have\[(a^2-b^2)^2\]which doesn't count.

Answer 5

dalvoron can u help me??

Answer 6

??