Q.
If the roots α,β of the equation px2+qx+r=0 are real and of opposite sign (where p,q,r are real coefficient), then the roots of the equation α(x−β)2+β(x−α)2=0 are
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Complex Numbers and Quadratic Equations
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Solution:
The equation α(x−β)2+β(x−α)2=0 has the product of its roots given by (α+β)αβ(α+β)=αβ<0 (Given) [(α+β)x2−2x(αβ+αβ)+αβ(α+β)=0] i.e. (α+β)x2−4αβx+αβ(α+β)=0
Also the discriminant 16α2β2−4αβ(α+β)2=−4αβ[(α+β)2−4αβ]=−4αβ(α−β)2>0 So, the roots are of opposite sign and are real.