Make bottom number same
ok, so remember
(a-b)(a+b)=a²+b²
so
to get from (y-x) to (y²-x²), multiply 2nd fraction by (y+x)
so multiply 2nd fraction by (y+x)/(y+x)
=
=
ok, so remember
(a-b)(a+b)=a²+b²
so
to get from (y-x) to (y²-x²), multiply 2nd fraction by (y+x)
so multiply 2nd fraction by (y+x)/(y+x)