Introduction to Linear Polynomials | Exercise 2.1

Question 1

Find the degrees of the following polynomials:

(i) 2x2−5x+32x^2 - 5x + 3

(ii) y3+2y−1y^3 + 2y - 1

(iii) −9-9

(iv) 4z−34z - 3

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Solution
Understand the Question
  • The degree of a polynomial is the highest exponent (power) of the variable in the polynomial with a non-zero coefficient.
  • For a non-zero constant polynomial (like a standalone number cc), it can be written as c⋅x0c \cdot x^0, so its degree is always 00.
  • For linear terms like zz, the exponent is understood to be 11 (since z=z1z = z^1).

(i) 2x2−5x+32x^2 - 5x + 3

Step 1 · Find the Degree of 2x2−5x+32x^2 - 5x + 3

Diagram 1

In the polynomial 2x2−5x+32x^2 - 5x + 3, the powers of the variable xx in each term are 22, 11, and 00.

Highest power=2\text{Highest power} = 2

Degree=2\text{Degree} = 2

Answer

(i) 22

(ii) y3+2y−1y^3 + 2y - 1

Step 1 · Find the Degree of y3+2y−1y^3 + 2y - 1

In the polynomial y3+2y−1y^3 + 2y - 1, the powers of the variable yy in each term are 33, 11, and 00.

Highest power=3\text{Highest power} = 3

Degree=3\text{Degree} = 3

Answer

(ii) 33

(iii) −9-9

Step 1 · Find the Degree of −9-9

The given polynomial is a non-zero constant polynomial.

We can write −9-9 as −9x0-9x^0.

Highest power=0\text{Highest power} = 0

Degree=0\text{Degree} = 0

Answer

(iii) 00

(iv) 4z−34z - 3

Step 1 · Find the Degree of 4z−34z - 3

In the polynomial 4z−34z - 3, the powers of the variable zz in each term are 11 and 00.

Highest power=1\text{Highest power} = 1

Degree=1\text{Degree} = 1

Answer

(iv) 11

Common Mistakes
  • Constant Polynomial Error: Assuming a non-zero constant like −9-9 has no degree or degree 11. A non-zero constant can be written as −9x0-9x^0, giving it a degree of 00.
  • Missing Implied Exponents: Forgetting that a variable with no written power (e.g., 4z4z) has an exponent of 11, not 00.
  • Confusing Coefficients and Exponents: Looking at the largest coefficient (such as 44 or −9-9) instead of the highest power of the variable.

More questions in Exercise 2.1

Q1

Find the degrees of the following polynomials:

(i) 2x2−5x+32x^2 - 5x + 3

(ii) y3+2y−1y^3 + 2y - 1

(iii) −9-9

(iv) 4z−34z - 3

Q2

Write polynomials of degrees 1, 2 and 3.

Q3

What are the coefficients of x2x^2 and x3x^3 in the polynomial x4−3x3+6x2−2x+7x^4 - 3x^3 + 6x^2 - 2x + 7?

Q4

What is the coefficient of zz in the polynomial 4z3+5z2−114z^3 + 5z^2 - 11?

Q5

What is the constant term of the polynomial 9x3+5x2−8x−109x^3 + 5x^2 - 8x - 10?

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