Like and unlike terms

Like terms have same variables

Unlike terms have different variables

Let’s look at some examples

2𝑥, 3𝑥

2𝑥 & 3𝑥 have the same variable 𝑥

So they are like terms

3𝑥 ² y, 2y𝑥 ²

3x ² y has variable 𝑥 ² y

2yx ² has variable y𝑥 ² i.e 𝑥 ² y                      (As x ² y = y𝑥 ² )

So, they are like terms

−4𝑥y, 3xy

−4𝑥y has variable 𝑥y

   3𝑥y has variable 𝑥y

−4xy and 3xy have same variable xy.

So, they are like terms.

4𝑥y, 3𝑥

4𝑥y has variable 𝑥y

3𝑥 has variable 𝑥

4𝑥y, 3𝑥 have different variables.

So, they are unlike terms.

21z, 39z

21z  has variable z

39z has Variable z

21z and 39z has same variable z

So, they are like terms.

8, 9

Since both 8 & 9 do not have a variable

∴ They are like terms