NCERT Solutions Class 9 Maths Chapter 2 — Introduction to Linear Polynomials#

Chapter 2 introduces linear polynomials of the form $ax + b$ — expressions in one variable with degree one. You will identify coefficients, evaluate polynomials, translate word problems into linear equations, and see how the graph of $y = ax + b$ is a straight line whose slope is $a$ and y-intercept is $b$.

Exercises#

• Exercise Set 2.1 — Degree of a polynomial, coefficients, constant term (5 questions)
• Exercise Set 2.2 — Evaluating linear and quadratic polynomials; word problems (ages, ratios, coins, fencing, rectangles) (7 questions)
• Exercise Set 2.3 — Linear patterns from real-life growth/decay (5 questions)
• Exercise Set 2.4 — Linear growth and decay: plant, phone value, village population, prepaid recharge (4 questions)
• Exercise Set 2.5 — Finding $a$ and $b$ in $y = ax + b$ from two known points (3 questions)
• Exercise Set 2.6 — Graphs of $y = ax + b$: role of slope $a$ and intercept $b$, parallel lines (1 question)
• End-of-Chapter Exercises — Digit problems, Kelvin–Fahrenheit, work–distance, matchstick hexagon pattern (14 questions)

What you will learn#

• Linear polynomials $ax + b$: degree, coefficients and the constant term.
• Using linear polynomials for real patterns — savings, growth and decay, fares and charges.
• Finding $a$ and $b$ in $y = ax + b$ from given values.
• Graphing $y = ax + b$ and what $a$ and $b$ do to the line.

Key formulas and results#

• The graph of $y = ax + b$ is a straight line that crosses the y-axis at $b$.
• The zero of $ax + b$ is $x = -\dfrac{b}{a}$.

Read and revise#

• NCERT Class 9 Maths Chapter 2 (PDF) — the Ganita Manjari Part I chapter itself.
• All Class 9 Maths chapters from Ganita Manjari Part I and Part II.

Frequently asked questions#