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Pair Of Linear Equations In Two Variables

Question
CBSEENMA10006813

For what value of m, the pair of linear equations mx = 2y, 2x - y + 5 = 0 has unique solution.

Solution
Given pair of linear equations are :
mx space equals space 2 straight y
rightwards double arrow space mx space minus space 2 straight y space equals space 0
and space 2 straight x minus straight y plus 5 space equals space 0
Here,  we  have
straight a subscript 1 equals straight m subscript 1 comma space space straight b subscript 1 equals negative 2
and space straight a subscript 2 equals 2 comma space straight b subscript 2 equals negative 1
For unique solution :
straight a subscript 1 over straight a subscript 2 not equal to straight b subscript 1 over straight b subscript 2
rightwards double arrow space space straight m over 2 not equal to fraction numerator negative 2 over denominator negative 1 end fraction
rightwards double arrow space straight m not equal to 4
∴ The given system of equations has unique solution for all real values of k other than 4.