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Which of the following pairs of linear equations has unique solution, no solution, or infinitely many solutions. In case there is a unique solution, find it by using cross multiplication method. (iii) 3x - 5y = 20 6x - 10y = 40

Q1.    Which of the following pairs of linear equations has unique solution, no solution, or infinitely many solutions. In case there is a unique solution, find it by using cross multiplication method.

                (iii)    \\3x -5 y = 20\\ 6x - 10y = 40

Answers (1)
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Given The equations,

\\3x -5 y = 20..........(1)\\ 6x - 10y = 40........(2)

Comparing these equations with a_1x+b_1y+c_1=0\:and\:a_2x+b_2y+c_2=0, we get

\frac{a_1}{a_2}=\frac{3}{6}=\frac{1}{2}

\frac{b_1}{b_2}=\frac{-5}{-10}=\frac{1}{2}

\frac{c_1}{c_2}=\frac{20}{40}=\frac{1}{2}

As we can see, 

\frac{a_1}{a_2}=\frac{b_1}{b_2}=\frac{c_1}{c_2}

Hence, the pair of equations has infinitely many solutions.

 

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