Question

I am not sure what this is asking for, can someone help me please?! Thank you!

Okay this is my back to school review on khan academy, I solved the problem, easy as pie, I got x^2-81 , but what on earth is it asking for in the other part? I will put a screenshot in the comments, thank you!

Answer 1

first expand (x - 9)(x + 9)

then compare it term by term with

x^2 + rx + t

Answer 2

I know that, but x^2-81 does not match terms???

Answer 3

x^2 + rx + t
x^2 = 0x - 81

Answer 4

* that is + 0x (typo)

Answer 5

so r = 0
and t = ?

Answer 6

compare like terms

Answer 7

they want you to notice that 0 can make things "disappear"

Answer 8

yea