Question

x/a+x/b=2 ,ax-by=a²-b²

Answer 1

x/a + y/b = 2       ---(1)
ax-by= a2 - b2  ----(2)
x/a = 2-y/b
x    = 2a - ay/b
substitute x in (2).
a(2a - ay/b) - by = a2 - b2
2a2 - a2y/b - by = a2 -b2
a2 - a2y/b -by+ b2 = 0
a2 +b2 = a2y/b + by
a2 + b2 = (a2y + b2y)/b
b(a2 + b2) = (a2 + b2)y
therefore, y = b

x/a +y/b =2  -----(1)
x/a +b/b =2
x/a =2-1
x = a
therefore x=a

Answer 2

You must use biquadratic rules. verify your Q again