# NCERT Solutions for Class 9 Maths Chapter 4 Linear Equations in Two Variables Ex 4.1

These NCERT Solutions for Class 9 Maths Chapter 4 Linear Equations in Two Variables Ex 4.1 Questions and Answers are prepared by our highly skilled subject experts.

## NCERT Solutions for Class 9 Maths Chapter 4 Linear Equations in Two Variables 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.
Solution:
Let the cost of a notebook is Rs. x and the cost of a pen is Rs. y
According to question
x = 2y or, x – 2y = 0
Therefore the linear equation in two variables to represent this statement is 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.$$\bar{35}$$
(ii) x – $$\frac {y}{5}$$ – 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) We have given that
2x + 3y = 9.$$\bar{35}$$
2x + 3y – 9.$$\bar{35}$$ = 0
Now, it is the form of ax + by + c = 0
Therefore the values of a, b and c are 2, 3 and -9.$$\bar{35}$$ respectively.

(ii) We have given that
x – $$\frac {y}{5}$$ – 10 = 0
We can also write
1x + ($$\frac {-y}{5}$$) y + (-10) = 0
Now, it is in the form of ax + by + c = 0
Therefore values of a, b and c are 1, $$\frac {-y}{5}$$, and -10 respectively.

(iii) We have given that
-2x + 3y = 6
or, -2x + 3y – 6 = 0
We can also write
(-2)x + 3y + (-6) = 0
Now, it is in the form of ax + by + c = 0
Therefore, the values of a, b and c are -2, 3 and -6 respectively. (iv) We have given that,
x = 3y
or, x – 3y = 0
We can also write
1x + (-3)y + 0 = 0
Now, it is in the form of ax + by + c = 0 and the values of a, b and c are 1, -3 and 0 respectively.

(v) We have given that
2x = -5y
or, 2x + 5y = 0
We can also write 2x + 5y + 0 = 0
Now, it is in the form of ax + by + c = 0.
Therefore, the values of a, b and c are 2, 5 and 0 respectively.

(vi) We have given that
3x + 2 = 0
We can also write 3x + 0y + 2 = 0
Now, it is in the form of ax + by + c = 0
Therefore, the values of a, b and c are 3, 0 and 2 respectively.

(vii) y – 2 = 0
We can also write,
0x + 1y + (-2) = 0
Now, it is in the form of ax + by + c = 0.
Therefore, the values of a, b and c are 0, 1 and -2 respectively. (viii) we have given that
5 = 2x
or, 2x – 5 = 0
We can also write
2x + 0y + (-5) = 0
Now it is in the form of ax + by + c = 0.
Therefore, the values of a, b and c are 2, 0 and (-5) respectively.

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