Question

find first term of an ap whose 2nd term is (x-y) and 5th term is (x+y)

Answer 1

a2 = (x-y)
a + (2-1)d = (x-y)
a + d = (x-y) ----(1)

a5 = (x+y)
a + (5-1)d = (x+y)
a + 4d = (x+y) ----(2)

(2)-(1)
a+4d = (x+y)
a + d = (x-y)

3d = 2y
d = 2y/3

sub value of d in (1)

a + 2y/3 = (x-y)
a = (x-y) - 2y/3
a = 3x-3y-2y/3
a = 3x-5y/3