﻿ Class 9 NCERT Math Solution
﻿
TOPICS
Exercise - 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.
(Take the cost of a notebook to be Rs. x and that of a pen to be Rs. y).

Solution :-
```  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
```

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 = 9.35
(ii) x- 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 = 9.35
2x + 3y - 9.35 = 0
Compairing the equation with equation ax + by + c = 0
a = 2, b = 3, c = - 9.35

(ii) x- y/5 - 10 = 0
5x - y - 50 = 0
Compairing the equation with equation ax + by + c = 0
a = 5, b = -1, c = -50

(iii) –2x + 3y = 6
-2x + 3y - 6 = 0
Compairing the equation with equation ax + by + c = 0
a = -2, b = 3, c = -6

(iv) x = 3y
x - 3y = 0
Compairing the equation with equation ax + by + c = 0
a = 1, b = -3, c = 0

(v) 2x = –5y
2x + 5y = 0
Compairing the equation with equation ax + by + c = 0
a = 2, b = 5 c = 0

(vi) 3x + 2 = 0
Compairing the equation with equation ax + by + c = 0
a = 3, b = 0, c = 2

(vii) y – 2 = 0
Compairing the equation with equation ax + by + c = 0
a = 0, b = 1, c = -2

(viii) 5 = 2x
2x - 5 = 0
Compairing the equation with equation ax + by + c = 0
a = 2, b = 0, c = -5
```
CLASSES