4/x - 4/y
_________
2 - 2
y X
__________
4
thats y to the 2nd power and x to the second power
4/x - 4/y divided by y^2 - x^2 / 4
4/x - 4/y = (4y -4x )/xy taking the LCD
y^2 -x^2 = (y +x )(y-x) using the differences of square formula
it would be 4y- 4x / xy divided by (y-x)(y+x) / 4
Do the reciprocal and multiply with the fractions
4 (y-x ) .xy * 4 / (y-x)(y+x)
Answer is 16/xy(y+x) y-x is common on both top and bottom.. Cancel it