NCERT Solutions
Class 9 - Mathematics - Chapter 4: LINEAR EQUATIONS IN TWO VARIABLES
EXERCISE 4.1

Question. 1

The cost of a notebook is twice the cost of a pen. Write a linear equation in two variables to represent this statement. (Take the cost of a notebook to be ₹x and that of a pen to be ₹y.)

Answer:

x − 2y = 0

Question. 2

Express the following linear equations in the form \(ax + by + c = 0\) and indicate the values of \(a, b, c\) in each case:

(i) \(2x + 3y = 9.35\)
(ii) \(x - \dfrac{y}{5} - 10 = 0\)
(iii) \(-2x + 3y = 6\)
(iv) \(x = 3y\)
(v) \(2x = -5y\)
(vi) \(3x + 2 = 0\)
(vii) \(y - 2 = 0\)
(viii) \(5 = 2x\)

Answer:

(i) \(2x + 3y - 9.35 = 0;\ a = 2,\ b = 3,\ c = -9.35\)

(ii) \(x - \dfrac{y}{5} - 10 = 0;\ a = 1,\ b = -\dfrac{1}{5},\ c = -10\)

(iii) \(-2x + 3y - 6 = 0;\ a = -2,\ b = 3,\ c = -6\)

(iv) \(x - 3y + 0 = 0;\ a = 1,\ b = -3,\ c = 0\)

(v) \(2x + 5y + 0 = 0;\ a = 2,\ b = 5,\ c = 0\)

(vi) \(3x + 0y + 2 = 0;\ a = 3,\ b = 0,\ c = 2\)

(vii) \(0x + 1y - 2 = 0;\ a = 0,\ b = 1,\ c = -2\)

(viii) \(-2x + 0y + 5 = 0;\ a = -2,\ b = 0,\ c = 5\)

NCERT Solutions Class 9 – Mathematics – Chapter 4: LINEAR EQUATIONS IN TWO VARIABLES – EXERCISE 4.1 | Detailed Answers