Give three examples of binomials that are not a difference of squares

. x2 - 25: solution . 16x4 - 100 50x2 - 72   . x2 - 25

first we check that the binomial is a difference of squares. 
x2 is a perfect square, and so is 25, so yes we have a difference of squares. 
the square root of x2 is x, and the square root of 25 is 5 
so our answer is (x - 5)(x + 5)  

16x4 - 100

16x4 is a perfect square, as is 100, so we do have a difference of squares 
Here we must first factor out the common factor, if we do not our answer will not be completely factored. 
Our common factor is 4, giving us 4(4x4 - 25) 
the square root of 4x4 is 2x2, the square root of 25 is 5. 
so our answer is 4(2x2 - 5)(2x2 + 5)50x2 - 72Here neither 50x2 nor 72 are perfect squares, but we must first take out the common factor 
the common factor is 2, giving us 2(25x2 - 36) 
Now both 25x2 and 36 are perfect squares so we have a difference of squares. 
The square root of 25x2 is 5x and the square root of 36 is 6. 
so our answer is 2(5x - 6)(5x + 6)

HOPE I HELPED