Class 9 Maths Ganita Manjari Chapter 2 Solutions (NCERT 2026–27) – Introduction to Linear Polynomials
These Class 9 Maths Ganita Manjari Chapter 2 solutions cover Introduction to Linear Polynomials from the new NCF-2023 textbook (2026–27). Every exercise is solved step by step so you can understand each concept and revise the whole chapter quickly.
Chapter 2 Overview
Chapter 2 of Ganita Manjari, Introduction to Linear Polynomials, builds on algebraic expressions to define polynomials in one variable and their degree, then focuses on linear polynomials (degree 1). It shows how linear expressions model real-life linear patterns, linear growth and decay, and linear relationships of the form y = ax + b, and how to plot these as straight lines. The Class 9 Maths Ganita Manjari Chapter 2 solutions below work through every exercise step by step.
Key Concepts & Definitions
Polynomial (in one variable): an algebraic expression like x2 + 5x + 3 made of terms with whole-number powers of the variable.
Degree: the highest power of the variable. Degree 1 = linear, 2 = quadratic, 3 = cubic, 0 = constant.
Linear polynomial: a polynomial of degree 1, e.g. 2x + 3 or 5 − 4y.
Linear pattern: a sequence in which the difference between consecutive terms is constant.
Linear growth / decay: a quantity that increases (growth) or decreases (decay) by a fixed amount over equal intervals.
Linear relationship: y = ax + b, a straight line with slope a and y-intercept b; when b = 0 the line passes through the origin.
Key Facts & Formulas
Value of a polynomial: substitute the given value of the variable and simplify.
Linear relationship: y = ax + b — a = slope (rate of change), b = y-intercept (value when x = 0).
Plotting a line: find any two points (e.g. x = 0 and one more), plot and join them.
Parallel lines: have the same slope a (only b differs). Growth ⇒ a > 0; decay ⇒ a < 0.
Exercise Set 2.1
1. Find the degrees of the following polynomials: (i) 2x2 – 5x + 3 (ii) y3 + 2y – 1 (iii) –9 (iv) 4z – 3
2. Write polynomials of degrees 1, 2 and 3.
3. What are the coefficients of x2 and x3 in the polynomial x4 – 3x3 + 6x2 – 2x + 7?
4. What is the coefficient of z in the polynomial 4z3 + 5z2 – 11?
5. What is the constant term of the polynomial 9x3 + 5x2 – 8x – 10?
Exercise Set 2.2
1. Find the value of the linear polynomial 5x – 3 if: (i) x = 0 (ii) x = –1 (iii) x = 2
2. Find the value of the quadratic polynomial 7s2 – 4s + 6 if: (i) s = 0 (ii) s = –3 (iii) s = 4
3. The present age of Salil’s mother is three times Salil’s present age. After 5 years, their ages will add up to 70 years. Find their present ages.
4. The difference between two positive integers is 63. The ratio of the two integers is 2 : 5. Find the two integers.
5. Ruby has 3 times as many two-rupee coins as she has five-rupee coins. If she has a total ₹88, how many coins does she have of each type?
6. A farmer cuts a 300 feet fence into two pieces of different sizes. The longer piece is four times as long as the shorter piece. How long are the two pieces?
7. If the length of a rectangle is three more than twice its width and its perimeter is 24 cm, what are the dimensions of the rectangle?
Exercise Set 2.3
1. A student has ₹500 in her savings bank account. She gets ₹150 every month as pocket money. How much money will she have at the end of every month from the second month onwards? Find a linear expression to represent the amount she will have in the nth month.
2. A rally starts with 120 members. Each hour, 9 members drop out of the group. How many members will remain after 1, 2, 3, … hours? Find a linear expression to represent the number of members at the end of the nth hour.
3. Suppose the length of a rectangle is 13 cm. Find the area if the breadth is (i) 12 cm, (ii) 10 cm, (iii) 8 cm. Find the linear pattern representing the area of the rectangle.
4. Suppose the length of a rectangular box is 7 cm and breadth is 11 cm. Find the volume if the height is (i) 5 cm, (ii) 9 cm, (iii) 13 cm. Find the linear pattern representing the volume of the rectangular box.
5. Sarita is reading a book of 500 pages. She reads 20 pages every day. How many pages will be left after 15 days? Express this as a linear pattern.
Exercise Set 2.4
1. Suppose a plant has height 1.75 feet and it grows by 0.5 feet each month. (i) Find the height after 7 months. (ii) Make a table of values for t varying from 0 to 10 months. (iii) Find an expression that relates h and t, and explain why it represents linear growth.
2. A mobile phone is bought for ₹10,000. Its value decreases by ₹800 every year. (i) Find the value after 3 years. (ii) Make a table of values for t from 0 to 8 years. (iii) Find an expression relating v and t, and explain why it represents linear decay.
3. The initial population of a village is 750. Every year, 50 people move from a nearby city to the village. (i) Find the population after 6 years. (ii) Make a table of values for t from 0 to 10 years. (iii) Find an expression relating P and t, and explain why it represents linear growth.
4. A telecom company charges ₹600 for a recharge scheme. The prepaid balance is reduced by ₹15 each day after the recharge. (i) Write an equation for the remaining balance b(x) after x days. Explain why it represents linear decay. (ii) After how many days will the balance run out? (iii) Make a table of values for x from 1 to 10 days.
Exercise Set 2.5
1. A learning platform charges a fixed monthly fee plus a cost per module. When 10 modules were accessed the bill was ₹400; for 14 modules it was ₹500. If y = ax + b, find a and b.
2. A gym charges a fixed monthly fee plus a cost per hour of badminton. For 10 hours the bill was ₹800; for 15 hours it was ₹1100. If y = ax + b, find a and b.
3. The relation between Celsius and Fahrenheit is °C = a·°F + b. Given ice melts at 0°C / 32°F and water boils at 100°C / 212°F, find a and b.
Exercise Set 2.6
1. Draw the graphs of the following sets of lines. In each case, reflect on the role of ‘a’ and ‘b’. (i) y = 4x, y = 2x, y = x (ii) y = –6x, y = –3x, y = –x (iii) y = 5x, y = –5x (iv) y = 3x – 1, y = 3x, y = 3x + 1 (v) y = –2x – 3, y = –2x, y = 2x + 3
Class 9 Maths Ganita Manjari Chapter 2 Solutions — End-of-Chapter Exercises
1. Write a polynomial of degree 3 in the variable x, in which the coefficient of the x2 term is –7.
2. Find the values of the following polynomials at the indicated values of the variables. (i) 5x2 – 3x + 7 if x = 1 (ii) 4t3 – t2 + 6 if t = a
3. If we multiply a number by 5/2 and add 2/3 to the product, we get –7/12. Find the number.
4. A positive number is 5 times another number. If 21 is added to both the numbers, then one of the new numbers becomes twice the other new number. What are the numbers?
5. If you have ₹800 and you save ₹250 every month, find the amount you have after (i) 6 months (ii) 2 years. Express this as a linear pattern.
*6. The digits of a two-digit number differ by 3. If the digits are interchanged, and the resulting number is added to the original number, we get 143. Find both the numbers.
*7. Draw the graph of the following equations, and identify their slopes and y-intercepts. Also find where these lines cut the y-axis. (i) y = –3x + 4 (ii) 2y = 4x + 7 (iii) 5y = 6x – 10 (iv) 3y = 6x – 11 Are any of the lines parallel?
*8. The relation between Kelvin (x K) and Fahrenheit (y °F) is y = (9/5)(x – 273) + 32. (i) Find y if x = 313 K. (ii) If y = 158 °F, find x.
*9. Work done = constant force × distance. Express this as a linear equation in two variables (work w and distance d), and draw its graph for a constant force of 3 units. What is the work done when the distance travelled is 2 units?
*10. The graph of a linear polynomial p(x) passes through the points (1, 5) and (3, 11). (i) Find the polynomial p(x). (ii) Find where its graph cuts the axes. (iii) Draw the graph and verify.
*11. Let p(x) = ax + b and q(x) = cx + d be linear polynomials such that: (i) p(0) = 5; (ii) p(x) – q(x) cuts the x-axis at (3, 0); (iii) p(x) + q(x) = 6x + 4 for all real x. Find p(x) and q(x).
*12. Hexagons are made with matchsticks; a new hexagon shares a side with the previous one. (i) Draw the next two stages — how many matchsticks at each? (ii) Complete the table. (iii) Find the rule for the nth stage. (iv) Matchsticks for the 15th stage? (v) Can 200 matchsticks form a stage?
*13. p(x) = ax + b and q(x) = cx + d such that: (i) p(x) passes through (2, 3) and (6, 11); (ii) q(x) passes through (4, –1); (iii) q(x) is parallel to p(x). Find p(x) and q(x), and where each meets the x-axis.
*14. What do all linear functions of the form f(x) = ax + a, a > 0, have in common?
Common Mistakes to Avoid
Watch out for these
- Confusing a coefficient (the number) with the term or the variable.
- Forgetting that a non-zero constant has degree 0, and that a missing term means coefficient 0.
- Swapping slope (a) and y-intercept (b) in y = ax + b.
- Sign slips when transposing terms while solving a linear equation.
- Substituting negatives wrongly: (−3)2 = 9, not −9.
- Misreading word problems (which quantity is ‘twice’ or ‘5 times’ the other).
Practice MCQs & Assertion–Reason
1. The degree of the polynomial 7x − 4 is:
(a) 0 (b) 1 (c) 2 (d) 7
2. The value of 3x − 5 at x = 2 is:
(a) 1 (b) −1 (c) 11 (d) 6
3. A polynomial of degree 1 is called a:
(a) constant polynomial (b) linear polynomial (c) quadratic polynomial (d) cubic polynomial
4. In y = ax + b, the letter ‘a’ represents the:
(a) y-intercept (b) slope (c) constant term (d) degree
5. The y-intercept of the line y = 2x + 5 is:
(a) 2 (b) 5 (c) −5 (d) 0
6. The constant term of 4x2 − 3x + 9 is:
(a) 4 (b) −3 (c) 9 (d) 0
7. Two lines are parallel if they have the same:
(a) y-intercept (b) slope (c) x-intercept (d) degree
8. The line y = 3x passes through the point:
(a) (0, 3) (b) (3, 0) (c) (0, 0) (d) (1, 0)
9. If 2x + 1 = 9, then x =
(a) 3 (b) 4 (c) 5 (d) 8
10. The coefficient of x in 5x2 − 7x + 2 is:
(a) 5 (b) −7 (c) 2 (d) 7
For each Assertion–Reason question, choose: (A) Both Assertion and Reason are true and the Reason is the correct explanation of the Assertion; (B) Both are true but the Reason is not the correct explanation; (C) Assertion is true but Reason is false; (D) Assertion is false but Reason is true.
A-R 1. Assertion: The degree of a non-zero constant polynomial is 0.
Reason: A constant c can be written as c·x0.
A-R 2. Assertion: The lines y = 2x + 3 and y = 2x − 4 are parallel.
Reason: Parallel lines have equal slopes.
A-R 3. Assertion: The graph of y = ax (b = 0) passes through the origin.
Reason: When x = 0, y = 0 for the equation y = ax.
A-R 4. Assertion: 3x2 + 2x + 1 is a linear polynomial.
Reason: A linear polynomial has degree 1.
A-R 5. Assertion: In linear decay the slope is negative.
Reason: Linear decay means the quantity decreases by a fixed amount over equal intervals.
Quick Revision Summary
- A polynomial’s degree is the highest power of the variable; degree 1 = linear, 2 = quadratic, 3 = cubic, 0 = constant.
- To find a polynomial’s value, substitute the variable and simplify.
- A linear pattern has a constant difference between consecutive terms.
- Linear growth: increases by a fixed amount (slope a > 0); linear decay: decreases by a fixed amount (slope a < 0).
- A linear relationship is y = ax + b: a = slope, b = y-intercept; if b = 0 the line passes through the origin.
- Parallel lines share the same slope a (only b differs).
How to score full marks in this chapter
State the degree/coefficient/constant clearly, show each step when solving linear equations, and for word problems always define the variable first (“Let … = x”). For graph questions, write the line as y = ax + b, find two neat points, and label the slope and y-intercept.
Frequently Asked Questions
What is Class 9 Maths Ganita Manjari Chapter 2 about?
It covers polynomials and degree, linear polynomials, linear patterns, linear growth and decay, linear relationships y = ax + b, and plotting straight-line graphs.
What is a linear polynomial?
A linear polynomial is a polynomial of degree 1, such as 2x + 3 or 5 − 4y.
What do a and b mean in y = ax + b?
a is the slope of the line and b is the y-intercept (where the line cuts the y-axis).
Are these Class 9 Maths Ganita Manjari Chapter 2 solutions free?
Yes. All solutions are free and follow the official NCERT Ganita Manjari textbook for 2026–27.
