a/b + b/a = x

Question

a/b - b/a = y

in the equation above, if a is (not equal) to 0 and b is (not equal) to 0, which of the following must be equal to x^2-y^2?
a. 2
b. 4
c. ab/2
d. a^2 b^2/2
e. 4a^2b^2

Answer 1

x^2-y^2=(x-y)(x+y)=(2b/a)(2a/b)=4

Answer 2

so whts the answer