Question

How do you factor `9t^2-1` ?

Answer 1

I think you mean `9t^2-1`, in which case the answer is:

`9t^2-1 = (3t)^2-1^2 = (3t-1)(3t+1)`

...using the difference of squares identity:

`a^2 - b^2 = (a-b)(a+b)`