16y² - x² shows the difference of squares.
square root of 16y² is 4y
square root fo x² is x
(4y - x)(4y + x)
4y(4y + x) -x(4y + x)
16y² + 4xy -4xy - x²
16y² - x²
The middle two terms is equal to zero.
A difference of squares must be a binomial, so we want two terms. This rules out the third and fourth options.
If we look at the first two, we must check that both terms are perfect squares.
Look at the first one: is a perfect square (it's ), but is not a perfect square, because 10 is not a perfect square.
On the other hand, if we look at the second option, is the square of , and is clearly the square of . So, this is the difference of two squares.
1) (√10 y)²-(2x)²
=8(2x-5)² /4 -25