If a + \(\frac{1}{a + 1}\) = 5 Then find , (a + 1)3 + \(\frac{1}{(a + 1)^3}\)

212 219 216 213

213

Given = a + \(\frac{1}{a + 1}\) = 5 By adding 1 on both sides we get, (a + 1) + \(\frac{1}{a + 1}\) = 5 + 1 = 6 (a + 1)3 + \(\frac{1}{(a + 1)^3}\) = 63 - 3 × 1 = 213   Note - if x +  \(\frac{1}{x}\) = a then x3 + \(\frac{1}{x^3}\) =  a3 - 3a