Answer: x²−9
Step-by-step explanation:
A square number is obtained ehen we multiply a number to itself.
For example: 5 × 5 = 5² = 25 [It is a square number]
We can do this in expression too, For example: z×z =z²
From all the given options, only x²−9 has both terms as square.
∵ x² = x × x
and 9 = 3×3= 3²
So that, x²−9 =(x)²-(3)²
Hence, the correct option is x²−9.
