# NCERT Solutions for Class 9th Mathematics

## Chapter 4. Linear Equation In Two Variables

### Exercise 4.2

**Chapter 4. Linear Equation In Two Variables**

**Exercise 4.2**

**1. Which one of the following options is true, and why?**

*y *= 3*x *+ 5 has

(i) a unique solution, (ii) only two solutions,

Solution

(iii) infinitely many solution, because we can put many value of x and can get many solution of y.

**2. Write four solutions for each of the following equation**s:

(i) 2*x *+ *y *= 7

(ii) π*x *+ *y *= 9

*(iii) x *= 4*y*

Solution

**3. Check which of the following are solutions of the equation x – 2y = 4 and which are not:**

(i) (0, 2)

(ii) (2, 0)

(iii) (4, 0)

Solution :

x = 4 + 2y

(i) (0,2)

Putting value of x and y

= 0 = 4 + 2(2)

= 0 = 4 + 4 = 0 = 8, hence it is not a solution of eq

(ii) (2,0)

Putting value of x and y

= 2 = 4 + 2(0) = 2 = 4, hence it is also not a solution of eq

(iii) (4,0)

Putting value of x and y

= 4 = 4 + 2(0) = 4 = 4, hence it is a solution of eq

(v) (1,1)

Putting value of x and y

= 1 = 4 + 2(1) = 1= 6, hence, it is not a solution of eq

**4. Find the value of k, if x = 2, y = 1 is a solution of the equation 2x + 3y = k.**

Solution :

2x + 3y = k

Putting the value of x and y

2(2) + 3(1) = k = 4+3 = k = k = 7