Mathematics

Problem

Let

f(x) = \frac{x^2 + x - 1}{x^2 - x + 1}

, then the largest value of

f(x)

for all

x \in [-1, 3]

is: (a)

\frac{3}{5}

(b)

\frac{5}{3}

(c)

1

(d)

\frac{4}{3}