To simplify the expression 2x^2 - 11x - 21 / (x^2 + x - 56)(x + 1), we first factorize the quadratic terms in the denominator:

(x^2 + x - 56) = (x + 8)(x - 7)

Now we have the expression as 2x^2 - 11x - 21 / (x + 8)(x - 7)(x + 1)

Next, we factorize the numerator:

2x^2 - 11x - 21 = (2x + 3)(x - 7)

Now the expression becomes:

(2x + 3)(x - 7) / (x + 8)(x - 7)(x + 1)

Since we have (x - 7) in the numerator and the denominator, we can cancel them out:

(2x + 3) / (x + 8)(x + 1)

Therefore, the simplified form of the expression 2x^2 - 11x - 21 / (x^2 + x - 56)(x + 1) is (2x + 3) / (x + 8)(x + 1)