NCERT solution class 9 chapter 4 Linear Equations in Two Variables exercise 4.1 mathematics

EXERCISE 4.1

---

Q 1, Ex 4.1, Page No 68, Linear Equations In Two Variables, NCERT Class 9th

Page No 68:

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.
(Take the cost of a notebook to be Rs x and that of a pen to be Rs y.)

Answer:

Let the cost of a notebook and a pen be x and y respectively.
Cost of notebook = 2 × Cost of pen
x = 2y
x − 2y = 0

---

Q 2, Ex 4.1, Page No 68, Linear Equations In Two Variables, Class 9th Mathematics

Question 2:

Express the following linear equations in the form ax + by + c = 0 and indicate the values of a, b, c in each case:
(i) $2 x+3 y=9.\overline{35}$
(ii) $x-\frac{y}{5}-10=0$
(iii) − 2x + 3 y = 6
(iv) x = 3y (v) 2x = − 5y
(vi) 3x + 2 = 0
(vii) y − 2 = 0 (viii) 5 = 2x

Answer:

(i) $2 x+3 y=9.\overline{35}$

 $2 x+3 y-9.\overline{35}=0$
Comparing this equation with ax + by + c = 0,
a = 2, b = 3, $c=-9.3 \overline{5}$

(ii) $x-\frac{y}{5}-10=0$
Comparing this equation with ax + by + c = 0,
a = 1, b =$-\frac{1}{5}$, c = −10

(iii) − 2x + 3 y = 6
− 2x + 3 y − 6 = 0
Comparing this equation with ax + by + c = 0,
a = −2, b = 3, c = −6

(iv) x = 3y
1x − 3y + 0 = 0
Comparing this equation with ax + by + c = 0,
a = 1, b = −3, c = 0

(v) 2x = −5y
2x + 5y + 0 = 0
Comparing this equation with ax + by + c = 0,
a = 2, b = 5, c = 0

(vi) 3x + 2 = 0
3x + 0.y + 2 = 0
Comparing this equation with ax + by + c = 0,
a = 3, b = 0, c = 2

(vii) y − 2 = 0
0.x + 1.y − 2 = 0
Comparing this equation with ax + by + c = 0,
a = 0, b = 1, c = −2

(viii) 5 = 2x
− 2x + 0.y + 5 = 0
Comparing this equation with ax + by + c = 0,
a = −2, b = 0, c = 5

---