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CBSE · Class 10 · Mathematics · Pair of Linear Equations in Two VariablesSolve the following pair of linear equations by the elimination method: $$2x + 3y = 11$$ $$2x - 4y = -24$$\nHence, find the value of '$m$' for which $y = mx + 3$.

Step-by-Step Solution

Given equations:

  1. $2x + 3y = 11$ --- (Equation 1)
  2. $2x - 4y = -24$ --- (Equation 2)

Step 1: Eliminate $x$ by subtracting Equation (2) from Equation (1) $$(2x + 3y) - (2x - 4y) = 11 - (-24)$$ $$2x - 2x + 3y + 4y = 11 + 24$$ $$7y = 35$$ $$y = \frac{35}{7} = 5$$

Step 2: Substitute $y = 5$ in Equation (1) to find $x$ $$2x + 3(5) = 11$$ $$2x + 15 = 11$$ $$2x = 11 - 15$$ $$2x = -4$$ $$x = \frac{-4}{2} = -2$$ \nSo, $x = -2$ and $y = 5$.

Step 3: Find the value of '$m$' using $y = mx + 3$\nSubstitute $x = -2$ and $y = 5$ into the equation: $$5 = m(-2) + 3$$ $$5 - 3 = -2m$$ $$2 = -2m$$ $$m = \frac{2}{-2} = -1$$

Final Answer: $x = -2$, $y = 5$, and $m = -1$.

💡 Study Guide: This question tests core syllabus concepts from Pair of Linear Equations in Two Variables. For formulas, key summaries, and mock exam reference guides, read the full Pair of Linear Equations in Two Variables Revision Notes.
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