InterviewSolution
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InterviewSolution
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Suppose `alpha, beta` are roots of `ax^(2)+bx+c=0` and `gamma, delta` are roots of `Ax^(2)+Bx+C=0`. If `alpha,beta,gamma,delta` are in AP, then common difference of AP isA. `(1)/(4)((b)/(a)-(B)/(A))`B. `(1)/(3)((b)/(a)-(B)/(A))`C. `(1)/(2)((c)/(a)-(B)/(A))`D. `(1)/(3)((c)/(a)-(C)/(A))` |
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Answer» Correct Answer - A `:.alpha +beta=-(b)/(a),alphabeta=(c)/(a),alpha-beta=(sqrt(b^(2)-4ac))/(a)` and `gamma+delta=-(B)/(A),gammadelta=(C)/(A),gamma-delta=(sqrt(B^(2)-4AC))/(A)` Since, `alpha,beta, gamma` are in AP. Let `beta=alpha+D,gamma=alpha+2D" and "delta=alpha+3D` `:.alpha+ beta=(-b)/(a)" " implies alpha+alpha+D=-(b)/(a)` or `2alpha +D=-(b)/(a)" " ".......(i)"` and `gamma +delta=-(B)/(A)" " implies 2alpha +5D=-(B)/(A)" " "...........(ii)"` From Eqs. (i) and(ii), we get `4D=(-(B)/(A)+(b)/(a)) " or " D=(1)/(4)((b)/(a)-(B)/(A))`. |
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