Question

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

Answer 1

Answer:

difference of square identity

Step-by-step 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

Answer 2

Difference of Sqaures