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Mathematics · Pair of Linear Equations in Two Variables · NCERT Examples

Example 6

A complete, independently verified solution for NCERT Example 6.

Mathematics · Chapter 3 · NCERT Examples

Verified NCERT questions and solutionsSolutions are checked independently and follow the supplied NCERT chapter edition.

NCERT Example

Example 6

Two pencils and three erasers cost ₹9; four pencils and six erasers cost ₹18. Find each price.

Solution

Let the prices be x and y rupees.

2x+3y=9,4x+6y=182x+3y=9,\qquad4x+6y=18
x=93y2x=\frac{9-3y}{2}

Substitution in the second equation gives 18 = 18. The second equation is twice the first, so no unique pair of prices is determined.

Final answer

There are infinitely many solutions; the individual prices cannot be found uniquely.