NCERT Solutions Class 9 Maths
Chapter – 4 (Linear Equations in Two Variables)
The NCERT Solutions in English Language for Class 9 Mathematics Chapter – 4 Linear Equations in Two Variables Exercise 4.1 has been provided here to help the students in solving the questions from this exercise.
Chapter 4: Linear Equations in Two Variables
- NCERT Solution Class 9 Maths Ex – 4.2
- NCERT Solution Class 9 Maths Ex – 4.3
- NCERT Solution Class 9 Maths Ex – 4.4
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 ₹ x and that of a pen to be ₹ y)
Answer – Let the cost of a notebook be = ₹ x
Let the cost of a pen be = ₹ y
According to the condition, we have
Cost of a notebook =2 × Cost of a pen
x = 2 × y
x = 2y
x – 2y = 0
Thus, the required linear equation is 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 = 9.3
(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
Answer –
(i) 2x + 3y = 9.3
2x + 3y − 9.3 = 0
Comparing it with ax + by +c = 0,
we get a = 2, b = 3 and c= –9.3
(ii) x − − 10 = 0
x – y – 10= 0
Comparing it with ax + by + c = 0,
we get a =1, b = – and c = -10
(iii) –2x + 3y = 6
– 2x + 3y – 6 = 0
Comparing it with ax + by + c = 0,
We get, a = –2, b = 3 and c =-6
(iv) x = 3y
x – 3y = 0
Comparing it with ax + by + c = 0,
We get a = 1, b = -3 and c =0
(v) 2x = –5y
2x + 5y = 0
Comparing it with ax + by + c = 0,
We get a = 2, b = 5 and c = 0
(vi) 3x + 2 = 0
3x + 0y + 2 = 0
Comparing it with ax + by + c = 0,
We get a = 3, b = 0 and c = 2
(vii) y – 2 = 0
0x + 1y –2 = 0
Comparing it with ax + by + c = 0,
We get a = 0, b = 1 and c = –2
(viii) 5 = 2x
2x – 5 = 0
2x + 0y – 5 = 0
Comparing it with ax + by + c = 0,
We get a = 2, b = 0 and c = -5
