Question

What polynomial identity should be used to prove that 21 = 25 − 4?

Answer 1

Difference of Sqaures

Answer 2

difference of square identity

Explanation:

`21 = 25 - 4`

25 can be written as
`5*5=5^2`

4 can be written as
`2*2=2^2`

`25 - 4=5^2-2^2`

WE use difference of square identity

`a^2-b^2=(a+b)(a-b)`

`5^2-2^2=(5+2)(5-2)`

`21 = 25 - 4`

`21=5^2-2^2`

`21=(5+2)(5-2)`

`21=(7)(3)`

21=21 Hence proved.

We proved it using difference of squares identity