Exercise-4.1, Class 9th, Maths, Chapter 4, NCERT

Q1. The cost of a notebook is twice the cost of a pen.
(Take the cost of a notebook to be ₹x and that of a pen to be ₹y.)

Answer 1.
Equation: $x = 2 y$
(Or equivalently $x - 2 y = 0$ )

Q2. Express the following linear equations in the form $a x + b y + c = 0$ and indicate $a, b, c$ in each case:

(i) $2 x + 3 y = 9.35$
Rewrite: $2 x + 3 y - 9.35 = 0$
So $a = 2, b = 3, c = - 9.35$

(ii) $x - 5 y - 10 = 0$
(Already in required form.)
So $a = 1, b = - 5, c = - 10$

(iii) $- 2 x + 3 y = 6$
Rewrite: $- 2 x + 3 y - 6 = 0$
So $a = - 2, b = 3, c = - 6$

(iv) $x = 3 y$
Rewrite: $x - 3 y = 0$
So $a = 1, b = - 3, c = 0$

(v) $2 x = - 5 y$
Rewrite: $2 x + 5 y = 0$
So $a = 2, b = 5, c = 0$

(vi) $3 x + 2 = 0$
Rewrite: $3 x + 0 \cdot y + 2 = 0$
So $a = 3, b = 0, c = 2$

(vii) $y - 2 = 0$
Rewrite: $0 \cdot x + y - 2 = 0$
So $a = 0, b = 1, c = - 2$

(viii) $5 = 2 x$
Rewrite: $2 x - 5 = 0$ (i.e. $2 x + 0 \cdot y - 5 = 0$ ).
So $a = 2, b = 0, c = - 5$

👋Subscribe to
ProTeacher.in