f(x) = ...

  x - 1
  x
  x + 1
  x^2
  1
  1 / x
  -1 / x

f(x) = ...

  x
  e^x
  ln(x)
  sqrt(x)
  |x|
  x + sqrt(x)
  1 / (x - atan(x))

f(x) = ...

  1
  x
  x^2
  x^3
  x^4
  x^5
  x^6
  x^7
  x^8

f(x) = ...

  (x - 1)^2
  1 / (1 + x)
  x^2 + 1
  1 / (2 + x)
  (x + 1)^2
  x^2 - 1

f(x) = ...

  1 / x
  -1 / x
  1 / x^2
  -1 / x^2
  1 / (1 + x)
  -1 / (1 + x)
  tan(x)
  -tan(x)

f(x) = ...

  cos(x)
  cos(2 * x)
  cos(3 * x)
  cos(6 * x)
  sin(x)
  sin(2 * x)
  sin(3 * x)
  sin(6 * x)

f(x) = ...

  x^3
  x^4
  x^5
  e^x
  ln(x)
  atan(x)
  e^(ln(x) / 2)

f(x) = ...

  -sqrt(x)
  sqrt(x)
  sqrt(x) - 2
  ln(x)
  atan(x) - atan(x - 1)
  1 / x
  -1 / x

f(x) = ...

  1 / (1 + x)
  cos(x) / x
  sin(x) / x
  1 / (1 + x^2)
  |sin(x) / x|
  1 - sqrt(|x[)
  plg(2 * x - 1)

f(x) = ...

  Wtf is that
  (cos(e^x - ln(x)) + atan(3 - cos(x)))^(85 + sinh(sin(sinh(x^7/2 - x^5/2))) * 0.21)
  x^3 + 1
  e^(2 * x) - e^x
  e^(3 * x) - e^(2 * x)
  e^(4 * x) - e^(3 * x)
  1 / (x^4 - 1)