Ncert Solutions for Class 9
Linear Equations in Two Variables
Linear Equations in Two Variables
Exercise 4.1
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).
(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)
Linear Equations in Two Variables
Exercise 4.2
1. Which one of the following options is true, and why? y = 3x + 5 has
(i) a unique solution,
(ii) only two solutions,
(iii) infinitely many solutions.
2. Write four solutions for each of the following equations:
(i) (2x + y = 7)
(ii) (πx + y = 9)
(iii) (x = 4y)
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) (iv) ((sqrt{2}, 4sqrt{2})) (v) (1, 1)
4. Find the value of k, if x = 2, y = 1 is a solution of the equation 2x + 3y = k.