Question

if one of the root of x^2+(1+k)x+2k=0 is twice other,then find (a^2+b^2)/ab

Answer 1

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=> Let the roots of the equation be p and p.

Sum of roots=2p=−2(k+1)=2p=−2(k+1)  So p=−1−kp=−1−k

Product of roots =p2=k2p2=k2   So p=kp=k  or p=−kp=−k

Substitute this value of p in the previous expression

k=−1−kk=−1−k So k=−1/2k=−1/2

The other value of p does not give any solution. Sok=−1/2k=−1/2

Hope that was useful.