Bihar Board Class 9th Maths Solutions Chapter 4 Linear Equations in Two Variables Ex 4.1 Textbook Questions and Answers.

## BSEB Bihar Board Class 9th Maths Solutions Chapter 4 Linear Equations in Two Variables Ex 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.

Solution:

Let the cost of a notebook be Rs x and that of a pen be Rs y. Since the cost of a notebook is twice the cost of pen. So, the required linear equation in two variables to represent the above statement is given by x = 2y.

Question 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\(\bar { 5 }\)

(ii) x – \(\frac { y }{ 5 }\) – 10 = 0

(iii) – 2x + 3y = 6

(iv) x = 3y

(v) 2x = – 5y

(vi) 3x + 2 = 0

(vii) y – 2 = 0

(viii) 5 = 2x

Solution:

(i) 2x + 3y = 9 can be written as 2x + 3y – 9 = 0.

On comparing it with ax + by + c = 0, we have

a = 2, b = 3 and c = – 9,

(ii) On.comparing x – \(\frac { y }{ 5 }\) – 10 = 6 with ax + 6y f c = 0, we have

a = 1, b = \(\frac { – 1 }{ 5 }\) and c = – 10.

(iii) – 2x i+ 3y = 6 can be written as – 2x + 3y – 6 = 0.

On comparing it With ax + by + c = 0, we have

a = – 2, b = 3 and c = – 6.

(iv) x- 3y can be written as x – 3y = 0.

On comparing it with ax + by + c – 0, we have a = 1, b = – 3 and c = 0.

(v) 2x = – 5y can be written as 2x + 5y = 0

On comparing it with ax + by + c = 0, we have

a = 2, b = 5 and c = 0.

(vi) On comparing 3x + 2 = 0 with ax + by + c = 0, we

a = 3, b = 0 and c = 2.

(vii) On comparing y – 2 = 0 with ax + by + c = 0, we

a = 0, b = 1 and c = – 2.

(viii) 5 = 2x can be written as 2x – 5 = 0.

On comparing with ax + by + c = 0, We have

a = 2, 6 = 0 and c = – 5