Question

Darius uses the polynomial identity (x−y)^2=x^2−2xy+y^2 to show that 9² = 81. What values can Darius use for x and y?

Answer 1

I don't know what the actual answer is but I do know that the tutor answer is wrong because it is not an option.

Answer 2

Darius can use x=10 and y=1

Explanation:

Darius wants to use the polynomial identity

`(x-y)^2=x^2-2xy+y^2`

to find 9²

Let x=10 and y=1

Then,

`(10-1)^2=10^2-2* 10* 1+1^2\\\\=100-20+1\\\\=80+1\\\\=81`

`(10-1)^2=81`

implies that 9² = 81

Hence, Darius can use x=10 and y=1