Example 2 - Chapter 3 Class 10 Pair of Linear Equations in Two Variables

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Example 2 Romila went to a stationery shop and purchased 2 pencils and 3 erasers for Rs 9. Her friend Sonali saw the new variety of pencils and erasers with Romila, and she also bought 4 pencils and 6 erasers of the same kind for Rs 18. Represent this situation algebraically and graphically. Let the cost of pencil be x. & Let the cost of eraser be y. Romila purchased 2 pencils & 3 erasers for Rs 9 2 × (Cost of pencil) + 3 × (Cost of eraser) = 9 2x + 3y = 9 2x + 3y – 9 = 0 Also, Sonali purchased 4 pencils and 6 erasers for Rs 18 4 × (Cost of pencil) + 6 × (Cost of eraser) = 18 4x + 6y = 18 4x + 6y – 18 = 0 Now, plotting equations 2x + 3y – 9 = 0 ...(1) 4x + 6y – 18 = 0 …(2) Solving (1) 2x + 3y – 9 = 0 3y = 9 − 2x y = (9 − 2𝑥)/3 Solving (2) 4x + 6y – 18 = 0 6y = 18 – 4x y = (18 − 4𝑥)/6