**Download NCERT Solutions for Class 9 Maths Chapter 4 Exercise 4.1**

**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 Rs x and that of a pen to be Rs y).**

**Solution:**

Let, the cost of a notebook = x

Cost of a pen = yThe cost of a notebook is twice the cost of a pen.

x = 2y

x – 2y = 0

**2. Express the following linear equations in the form ax + by + c = 0 and indicate the values of a, b and c in each case:**

**(i) 2x + 3y =
(ii) x – – 10 = 0
(iii) –2x + 3y = 6
(iv) x = 3y**

**(v) 2x = –5y**

(vi) 3x + 2 = 0

(vii) y – 2 =0

(viii) 5 =2x

(vi) 3x + 2 = 0

(vii) y – 2 =0

(viii) 5 =2x

**Solution:**

(i) Given equation : 2x + 3y =

It can be written as 2x + 3y – = 0

Comparing this equation with ax + by + c = 0 we get,

a = 2

b = 3

c =

(ii) Given equation : x – – 10 = 0

Comparing this equation with ax + by + c = 0 we get,

a = 1

b =

c = -10

(iii) Given equation : –2x + 3y = 6

It can be written as –2x + 3y – 6 = 0

Comparing this equation with ax + by + c = 0 we get,

a = -2

b = 3

c = -6

(iv) Given equation : x = 3y

It can be written as x – 3y + 0 = 0

Comparing this equation with ax + by + c = 0 we get,

a = 1

b = -3

c = 0

(v) Given equation : 2x = –5y

It can be written as 2x + 5y + 0 = 0

Comparing this equation with ax + by + c = 0 we get,

a = 2

b = 5

c = 0

(vi) Given equation : 3x + 2 = 0

It can be written as 3x + 0y + 2 = 0

Comparing this equation with ax + by + c = 0 we get,

a = 3

b = 0

c = 2

(vii) Given equation : y – 2 = 0

It can be written as 0x + y – 2 = 0

Comparing this equation with ax + by + c = 0 we get,

a = 0

b = 1

c = -2

(viii) Given equation : 5 = 2x

It can be written as -2x + 0y + 5 = 0

Comparing this equation with ax + by + c = 0 we get,

a = -2

b = 0

c = 5

**Download NCERT Solutions for Class 9 Maths Chapter 4 Exercise 4.1**

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