Fill in the blanks to make a quadratic whose roots are $1$ and $-1.$ x^2 + ___ x + ___
(x-1) = 0 produces a root of x =1
(x+1) = 0 produces a root of -1
multiply them together :
(x-1)(x+1) =0
x^2 + (0) x - 1 = 0 or simply x^2 -1 = 0