Show that (a–b)2, (a2+b2) and (a + b)2 are in A.P.
The terms given below are : (a–b)2, (a2+b2) and (a + b)2
Common difference, d1 = a2 + b2 – (a – b)2
d1 = a2 + b2 – (a2 + b2 - 2ab)
d1 = a2 + b2 – a2 - b2 + 2ab
d1= 2ab
Common difference, d2 = (a + b)2 – (a2 + b2)
d2 = a2 + b2 + 2ab – a2 –b2
d2 = 2ab
Since, d1 = d2 i.e. the common difference is same.
Therefore, the given terms are in A.P.