Simplify the rational expression.

x^2 + 2x - 35/x^2 + 4x - 21

To simplify the expression x^2 + 2x - 35 / x^2 + 4x - 21, we first factorize the numerator and denominator to get:

(x + 7)(x - 5) / (x + 7)(x - 3)

Now, we can cancel out the common factor of (x + 7) from both numerator and denominator to simplify the expression further:

(x - 5) / (x - 3)

So, the simplified rational expression is (x - 5) / (x - 3).