Question

# Given that p and q are the roots of the equation x2 – ax +b =0 and Dn= pn+qn. Find the value of Dn+1 aDn-bDn-1aDnbDnaDn + bDn-1Dn

Solution

## The correct option is A aDn-bDn-1Option (a)Best way to proceed is by assumption of values.Assume a quadratic equation. Let’s take x2+5x-6=0. Here the roots are p=1 and q=-6Thus, a = sum of roots = -5 and b= product of roots = -6D1= p1+q1 = -5D0 = 2D2 = 37Assume n=1We need to find Dn+1 = D2 = 37Look in the answer options for 37Option a is the only one which gives (-5)(-5)-(-6)(2) = 37

Suggest corrections