Class 9 Mathematics Chapter 2 Introduction to Linear Polynomials – Revision Notes

Every polynomial has a degree that decides its type — linear, quadratic or cubic — and this chapter focuses on the linear case, where the graph is always a straight line crossing the x-axis at its single zero.

Last Updated: September 23, 2026

Polynomials

• Terms based on number of terms: monomial (1), binomial (2), trinomial (3).
• Degree = highest power of variable.
• Linear: degree 1; Quadratic: degree 2; Cubic: degree 3.

Zero of a Polynomial

• Value of x where p(x) = 0.
• Linear polynomial ax+b: unique zero x = −b/a.

Graph

• Linear polynomial y = ax+b → straight line; crosses x-axis at the zero.

One-Line Summary

A linear polynomial (degree 1) always has exactly one zero, found by solving ax+b=0, and its graph is always a straight line crossing the x-axis at that zero.

Quick visual: a worked diagram from the full Solutions page, for reference.

Frequently Asked Questions

What is a linear polynomial, and how is it different from other polynomials?
A linear polynomial is a polynomial of degree one, meaning the highest power of the variable is 1, such as ax plus b; unlike quadratic or cubic polynomials, its graph is always a straight line.

How many zeroes can a linear polynomial have, and why?
A linear polynomial has exactly one zero, because setting the polynomial equal to zero and solving for the variable gives a single unique value, corresponding to the one point where the straight-line graph crosses the x-axis.

Written by Satish

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