f_{4}(x) = (sqrt((9 * x^(2)) + (7 * x)) - (4 * x)) / (x - 1)
L_{4} = Limit(f_{4}(x), 1)
f_{1}(x) = (-x^(4)) - (2 * x^(2)) + 1
L_{1} = Limit(f_{1}(x), Infinity)
f_{2}(x) = (-(x / (x + 1)^(3)))
L_{2} = Limit(f_{2}(x), 1)
f_{3}(x) = ((-x^(4)) - (2 * x^(2)) + 1) / ((3 * x^(4)) - 8)
L_{3} = Limit(f_{3}(x), -Infinity)
f_{5}(x) = (-(((3 * x^(2))) / (x^(2) - (2 * x) + 1)))
L_{5} = Limit(f_{5}, 1)
f_{6}(x) = (x^(3) + (4 * x^(2)) + (4 * x)) / (x^(2) + (2 * x))
L_{6} = Limit(f_{6}, -2)