f_1(x) = log((-x))
f_2(x) = (x + 2)^(2)
f_3(x) = (-ℯ^(x))
f_4(x) = (-x^(2))
f_5(x) = (3 * sin(x))
f_6(x) = x^(3) - 1
f_7(x) = abs(x^(2) - 1)
f_8(x) = ℯ^(x) - 2
f_9(x) = 1 / (x - 3)
g_1(x) = 1 / x^(2) - 1
g_2(x) = log(x + 1)
g_3(x) = (-log(x))