Question

If you factor y^2-81 COMPLETELY, would it just be (y-9)(y+9), or would it be something like y(3)(-3)y(3)(3)?

Answer 1

It would just be \((y-9)(y+9)\).

Answer 2

ok

Answer 3

but why

Answer 4

it said factor completely so shouldn't i factor the 9s

Answer 5

If you really feel the need to, you could also write it as \((y-3^2)(y+3^2)\), but in factoring \(y^2-81\), writing it as \(y^2-9^2\) or \(y^2-3^4\) isn't factoring the expression.

Answer 6

ok

Answer 7

Remember that you're factoring the entire expression , and not just the terms that are subtracted/added. So writing it as \((y-3^2)(y+3^2)\) isn't really factoring the expression anymore.

Answer 8

ok