### Linear Equations in Two Variables - Solutions

CBSE Class 9 Mathematics

NCERT Solutions

CHAPTER 4

Linear Equations in Two Variables(Ex. 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*).

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

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

*ax *+ *by *+ *c *= 0, to get the values of *a*, *b *and *c*.

Therefore, we can conclude that.

(v)

*ax *+ *by *+ *c *= 0 and indicate the values of *a*, *b *and *c*.

can also be written as

*ax *+ *by *+ *c *= 0, to get the values of *a*, *b *and *c*.

Therefore, we can conclude that.

(vi)

*ax *+ *by *+ *c *= 0 and indicate the values of *a*, *b *and *c*.

can also be written as

*ax *+ *by *+ *c *= 0, to get the values of *a*, *b *and *c*.

Therefore, we can conclude that.

(vii)

*ax *+ *by *+ *c *= 0 and indicate the values of *a*, *b *and *c*.

can also be written as

*ax *+ *by *+ *c *= 0, to get the values of *a*, *b *and *c*.

Therefore, we can conclude that.

(viii)

*ax *+ *by *+ *c *= 0 and indicate the values of *a*, *b *and *c*.

can also be written as

*ax *+ *by *+ *c *= 0, to get the values of *a*, *b *and *c*.

Therefore, we can conclude that.