Study Materials

NCERT Solutions for Class 9th Mathematics

Page 1 of 4

Chapter 4. Linear Equation In Two Variables

Exercise 4.1

Chapter 4. Linear Equation In Two Variables

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 'x' and that of a pen to be 'y' )

Solution:

Let the cost of pen = y

Let the cost of notebook= x

Then, According To Question,

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 = 9.35

Solution:

(i)  2x + 3y = 9.35

Expressing the equation in the form of ax + by + c = 0,

∴ 2x+3y-9.35= 0

On Comparing, We have

Then, a= 2, b= 3, c= -9.3

(ii)  x – 5y – 10 = 0

Solution:

(ii)  x – 5y – 10 = 0

Expressing the equation in the form of ax + by + c = 0,

∴  x- 5y - 10 = 0

On Comparing, We have

Then, a= 1, b= -5, c= -10

(iii)  –2x + 3y = 6

Solution:

(iii)  –2x + 3y = 6

Expressing the equation in the form of ax + by + c = 0,

∴ -2x + 3y - 6= 0

On Comparing, We have

Then, a=  -2, b= 3, c= -6

(iv)  x = 3y

Solution:

(iv)  x = 3y

Expressing the equation in the form of ax + by + c = 0,

x - 3y= 0

On Comparing, We have

Then, a= 1, b= -3, c= 0

(v)  2x = –5y

Solution:

(v)  2x = –5y

Expressing the equation in the form of ax + by + c = 0,

2x + 5y= 0

On Comparing, We have

Then, a= 2, b= 5, c= 0

(vi)  3x + 2 = 0

Solution:

(vi)  3x + 2 = 0

Expressing the equation in the form of ax + by + c = 0,

∴ 3x + 2= 0

On Comparing, We have

Then, a= 3, b= 0, c= 2

(vii)  y – 2 = 0

Solution:

(vii)  y – 2 = 0

Expressing the equation in the form of ax + by + c = 0,

∴ y-2= 0

On Comparing, We have

Then, a= 0, b= 1, c= -2

(viii)  5 = 2x

Solution:

(viii)  5 = 2x

Expressing the equation in the form of ax + by + c = 0,

2x - 5= 0

On Comparing, We have

Then, a= 2, b= 0, c= -5

Page 1 of 4

Chapter Contents: