Factorize:
a2−b2−2b−1
[a−b−1][a−b−1]
[a−b−1][a+b+1]
[a+b+1][a−b+1]
[a−b+1][a+b−1]
⇒a2−b2−2b−1
⇒a2−(b2+2b+1)
⇒a2−(b+1)2
∵(a+b)2=a2+b2+2ab, and a2−b2=(a−b)(a+b)
⇒[a−(b+1)][a+(b+1)]
⇒[a−b−1][a+b+1]
If a, b, c are in G.P., prove that:
(i) a(b2+c2)=c(a2+b2)
(ii) a2b2c2(1a3+1b3+1c3)=a3+b3+c3
(iii) (a+b+c)2a2+b2+c2=a+b+ca−b+c
(iv) 1a2−b2+1b2=1b2−c2
(v) (a+2b+2c)(a−2b+2c)=a2+4c2.