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Class 10 Maths · Chapter 2 · NCERT (jemh102)

Polynomials: common misconceptions

See the tempting mistake students make in Polynomials, why it feels right at first glance, and a worked visual example that shows the right idea.

The tempting mistake & worked visual

Are the zeros the coefficients?

Wrong

The zeros of x² − 5x + 6 are −5 and 6.

Why it feels right. They are the numbers visible in the expression.

Right

A zero is an input that makes the polynomial equal zero.

Worked example

Input xOutput x² − 5x + 6
−556
612
20
30
A zero is an x-value whose output is zero. Substitution checks all four proposed values.
  1. Substitute −5 and 6.
  2. The outputs are 56 and 12.
  3. Factor as (x − 2)(x − 3) to find x = 2 and x = 3, the inputs that make the output zero.

If your child says… (6 concept checks in this chapter)

As you work through Polynomials, listen for these everyday misunderstandings and use the prompt alongside each one.

1. Degree of a polynomial See how to teach this step →

If your child says… “The first term decides the degree.”

Ask together
Does writing the constant first remove the squared term?
What’s true
Find the greatest power after simplifying, wherever its term appears.
2. Value and zero of a polynomial See how to teach this step →

If your child says… “The input is 2, so the value is 2.”

Ask together
What remains after subtracting 2 from the input 2?
What’s true
The value comes from calculating with the input, not copying it.
3. Geometrical meaning of the zeroes of a polynomial See how to teach this step →

If your child says… “The bottom of the curve is a zero.”

Ask together
Is the bottom point on the horizontal axis or below it?
What’s true
A turning point counts only when its height is zero.
4. Zeroes of a quadratic polynomial See how to teach this step →

If your child says… “The brackets say minus 1 and minus 2, so those are the zeroes.”

Ask together
Which makes x minus 1 vanish: 1 or −1?
What’s true
A zero makes a bracket vanish when substituted.
5. Relationship between zeroes and coefficients See how to teach this step →

If your child says… “The product needs a minus sign too.”

Ask together
The zeroes here are 1 and 2; what does multiplying them give?
What’s true
For a quadratic, the product equals the constant divided by the leading coefficient.
6. Finding a quadratic polynomial See how to teach this step →

If your child says… “Only one polynomial can have these zeroes.”

Ask together
If an output is zero, what happens when you double it?
What’s true
Multiplying every term by the same nonzero number keeps exactly the same zeroes.

Use this chapter three ways