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+1aDn- bDn-1bDnaDnaDn+ bDn-1pDn

Solution

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

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