Linear Equations in Two Variables - Solutions

 CBSE Class 9 Mathematics

NCERT Solutions
CHAPTER 4
Linear Equations in Two Variables(Ex. 4.1)

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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).

Ans. Let the cost of a notebook be.

Let the cost of a pen be.

We need to write a linear equation in two variables to represent the statement, “Cost of a notebook is twice the cost of a pen”.

Therefore, we can conclude that the required statement will be= x -2y = 0 

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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) 

(ii) 

(iii) 

(iv) 

(v) 

(vi) 

(vii) 

(viii) 

Ans. (i) 

We need to express the linear equationin the form ax + by + c = 0 and indicate the values of a, b and c.

 can also be written as 

We need to compare the equationwith the general equation ax + by + c = 0, to get the values of a, b and c.

Therefore, we can conclude that.

(ii) 

We need to express the linear equationin the form ax + by + c = 0 and indicate the values of a, b and c.

can also be written as 

We need to compare the equationwith the general equation ax + by + c = 0, to get the values of a, b and c.

Therefore, we can conclude that.

(iii) 

We need to express the linear equationin the form ax + by + c = 0 and indicate the values of a, b and c.

can also be written as 

We need to compare the equationwith the general equation ax + by + c = 0, to get the values of a, b and c.

Therefore, we can conclude that.

(iv) 

We need to express the linear equationin the form ax + by + c = 0 and indicate the values of a, b and c.

can also be written as

We need to compare the equationwith the general equation ax + by + c = 0, to get the values of a, b and c.

Therefore, we can conclude that.

(v) 

We need to express the linear equationin the form ax + by + c = 0 and indicate the values of a, b and c.

can also be written as

We need to compare the equationwith the general equation ax + by + c = 0, to get the values of a, b and c.

Therefore, we can conclude that.

(vi) 

We need to express the linear equationin the form ax + by + c = 0 and indicate the values of a, b and c.

can also be written as 

We need to compare the equationwith the general equation ax + by + c = 0, to get the values of a, b and c.

Therefore, we can conclude that.

(vii) 

We need to express the linear equationin the form ax + by + c = 0 and indicate the values of a, b and c.

can also be written as 

We need to compare the equationwith the general equation ax + by + c = 0, to get the values of a, b and c.

Therefore, we can conclude that.

(viii) 

We need to express the linear equationin the form ax + by + c = 0 and indicate the values of a, b and c.

can also be written as 

We need to compare the equationwith the general equation ax + by + c = 0, to get the values of a, b and c.

Therefore, we can conclude that.