Pair of Linear Equations in Two Variables · Class 10 · CBSE Mathematics

Solve the following pair of linear equations using the substitution method: 2x + y = 7 and 4x - 3y = 1.

Practice question from Pair of Linear Equations in Two Variables (Class 10 · CBSE Mathematics), with the correct answer and a step-by-step solution.

medium · Subjective · Q-1D9427

Solve the following pair of linear equations using the substitution method: 2x+y=72x + y = 7 and 4x−3y=14x - 3y = 1.

Answer: From the first equation, express yy in terms of xx as y=7−2xy = 7 - 2x. Substituting this into the second equation gives 4x−3(7−2x)=14x - 3(7 - 2x) = 1, which simplifies to 4x−21+6x=14x - 21 + 6x = 1, or 10x=2210x = 22, yielding x=2.2x = 2.2 or 115\frac{11}{5}. Substituting x=115x = \frac{11}{5} back into y=7−2xy = 7 - 2x gives y=7−225=135y = 7 - \frac{22}{5} = \frac{13}{5}. Thus, the solution is x=115x = \frac{11}{5} and y=135y = \frac{13}{5}.

Solution

Express yy from the first equation as y=7−2xy = 7 - 2x and substitute it into the second equation. Solving the resulting linear equation in one variable gives x=115x = \frac{11}{5}. Substituting this value back yields y=135y = \frac{13}{5}.

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