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Examples

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Example 9 You are here

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Example 16 Important Deleted for CBSE Board 2023 Exams

Example 17 Deleted for CBSE Board 2023 Exams

Example 18 Important Deleted for CBSE Board 2023 Exams

Example 19 Important Deleted for CBSE Board 2023 Exams

Last updated at Dec. 18, 2020 by Teachoo

Example 9 Let us consider Example 2 in Section 3.3, i.e., the cost of 2 pencils and 3 erasers is Rs 9 and the cost of 4 pencils and 6 erasers is Rs 18. Find the cost of each pencil and each eraser. We formed the equations in Example 2 Our equations are 2x + 3y = 9 ...(1) 4x + 6y = 18 …(2) From (1) 2x + 3y = 9 2x = 9 – 3y x = ((𝟗 − 𝟑𝒚)/𝟐) Putting value of x in (2) 4x + 6y = 18 4 ((9 − 3𝑦)/2)+6𝑦=18 2 (9 – 3y) + 6y = 18 18 – 6y + 6y = 18 18 = 18 It is true for all values of x & y. Since the given equations have infinitely many solutions, That is why we cannot obtain a unique solution Reason :- The 2 equations given in question are 2x + 3y = 9 …(1) 4x + 6y = 18 …(2) From (2), 4x + 6y = 18 Diving both sides by 2 4𝑥/2 + 6𝑦/2 = 18/2 2x + 3y = 9 Which is equation same as equation (1) Hence both equation actually same So there can be infinite values of x and y For Example If y = 1, 2x + 3(1) = 9 2x + 3 = 9 2x = 9 – 3 2x = 6 x = 6/2 x = 3 If y = 0, 2x + 3(0) =9 2x + 0 = 9 2x = 9 x = 9/2 And so on