Answer:
( a+b) (a-b)
x^2 - 50
Step-by-step explanation:
The formula for difference of squares is
a^2 - b^2 = ( a+b) (a-b)
121x^2 -144 = (11x)^2 - 12^2 so this is the difference of squares
x^2 - 16y^2 = (x)^2 - (4y)^2 so this is the difference of squares
9x^2 -64 = (3x)^2-8^2 so this is the difference of squares
x^2 - 50 = (x)^2 - 2*(5)^2 this is not the difference of squares
