NCERT Exemplar Solutions
Class 10 - Mathematics - CHAPTER 3: Pair of Linear Equations in Two Variables - Exercise 3.1
Question 1

Question.  1

1. Graphically, the pair of equations
6x – 3y + 10 = 0
2x – y + 9 = 0
represents two lines which are

(A)

intersecting at exactly one point.

(B)

intersecting at exactly two points.

(C)

coincident.

(D)

parallel.

Detailed Answer with Explanation:

Step 1: Write equations in standard form.

Equation 1: \(6x - 3y + 10 = 0\) ⇒ coefficients \(a_1 = 6\), \(b_1 = -3\), \(c_1 = 10\).

Equation 2: \(2x - y + 9 = 0\) ⇒ coefficients \(a_2 = 2\), \(b_2 = -1\), \(c_2 = 9\).

Step 2: Compare the ratios of coefficients.

\(\dfrac{a_1}{a_2} = \dfrac{6}{2} = 3\)

\(\dfrac{b_1}{b_2} = \dfrac{-3}{-1} = 3\)

\(\dfrac{c_1}{c_2} = \dfrac{10}{9}\)

Step 3: Apply the condition for parallel lines.

If \(\dfrac{a_1}{a_2} = \dfrac{b_1}{b_2} \neq \dfrac{c_1}{c_2}\), then the lines are parallel and distinct.

Here, \(\dfrac{a_1}{a_2} = \dfrac{b_1}{b_2} = 3\), but \(\dfrac{c_1}{c_2} = \dfrac{10}{9}\), which is not equal to 3.

Conclusion: The two lines are parallel distinct lines.

NCERT Exemplar Solutions Class 10 – Mathematics – CHAPTER 3: Pair of Linear Equations in Two Variables – Exercise 3.1 | Detailed Answers