Question

Which equation has roots of
±
3
?

Answer 1

(x^2-9)

Explanation:

To have roots plusminus 3, the factors need to be (x+3) and (x-3)

You can FOIL those and multiply those out to get x^2-9.

Or you can remember the rule of Difference of Squares and know that the first term minus squared the second term squared is equal to first term + second term and first term minus second term.

Basically, (a^2-b^2) = (a+b)(a-b)

This does not work if it is (a^2+b^2)