f(x)=(x-1)(x+1)

Solution for f(x)=(x-1)(x+1) equation:

Simplifying
f(x) = (x + -1)(x + 1)

Multiply f * x
fx = (x + -1)(x + 1)

Reorder the terms:
fx = (-1 + x)(x + 1)

Reorder the terms:
fx = (-1 + x)(1 + x)

Multiply (-1 + x) * (1 + x)
fx = (-1(1 + x) + x(1 + x))
fx = ((1 * -1 + x * -1) + x(1 + x))
fx = ((-1 + -1x) + x(1 + x))
fx = (-1 + -1x + (1 * x + x * x))
fx = (-1 + -1x + (1x + x2))

Combine like terms: -1x + 1x = 0
fx = (-1 + 0 + x2)
fx = (-1 + x2)

Solving
fx = -1 + x2

Solving for variable 'f'.

Move all terms containing f to the left, all other terms to the right.

Divide each side by 'x'.
f = -1x-1 + x

Simplifying
f = -1x-1 + x