#### Chapter 13Â Linear Equations in Two VariablesÂ R.D. Sharma Solutions for Class 9th Exercise 13.1

**Exercise 13.1**

(i) -2x + 3y = 12

(ii) x - y/2 - 5 = 0

(iii) 2x + 3y = 9.35

(iv) 3x = -7y

(v) 2x+ 3 = 0

(vi) y - 5 = 0

(vii) 4 = 3x

(viii) y = x/2

**Solution**

(i) We are given

-2x + 3y = 12

-2x + 3y â€“ 12 = 0

Comparing the given equation with ax+ by+ c = 0

We get, a = â€“ 2; b = 3; c = -12

(ii) We are given

x â€“ y/2 â€“ 5= 0

Comparing the given equation with ax + by + c = 0 ,

We get, a = 1; b = -1/2, c = -5

(iii) We are given

2x + 3y = 9.35

2x + 3y â€“ 9.35 =0

Comparing the given equation with ax + by + c = 0

We get, a = 2 ; b = 3 ; c = -9.35

(iv) We are given

3x = -7y

3x + 7y = 0

Comparing the given equation with ax+ by + c = 0,

We get, a = 3 ; b = 7 ; c = 0

(v) We are given

2x + 3 = 0

Comparing the given equation with ax + by + c = 0,

We get, a = 2 ; b = 0 ; c = 3

(vi) We are given Y â€“ 5 = 0

Comparing the given equation with ax + by+ c = 0,

We get, a = 0; b = 1; c = -5

(vii) We are given

4 = 3x

3x-4 = 0

Comparing the given equation with ax + by + c = 0,

We get, a = 3; b = 0; c = -4

Â (viii) We are given

Y = x/2

Taking L.C.M => x â€” 2y = 0

Comparing the given equation with ax + by + c = 0 ,

We get, a = 1; b = -2; c = 0

2. Write each of the following as an equation in two variables:

(i) 2x = -3

(ii) y = 3

(iii) 5x = -7/2

(iv) y = 3/2 x

**Solution**

(i) We are given,

2x = -3

Now, in two variable forms the given equation will be

2x + 0y + 3=0

(ii) We are given,

y = 3

Now, in two variable forms the given equation will be

Â 0 x + y â€“ 3 = 0

(iii) We are given,

5x = -7/2

Now, in two variable forms the given equation will be

5x + 0y +7/2 = 0

10x + 0y â€“ 7 = 0

(iv) We are given,

y = 3/2 x

Now, in two variable forms the given equation will be

3/2 x - y + 0 = 0

â‡’ 3x - 2y + 0 = 0

3. The cost of ball pen is Rs 5 less than half of the cost of fountain pen. Write this statement as a linear equation in two variables.

**Solution**

Let the cost of fountain pen be y and cost of ball pen be x.

According to the given equation, we have

x = y/2 - 5

â‡’ 2x = y - 10

â‡’ 2x - y + 10 = 0