Pick the odd thing out:
Each of the questions follow a definite pattern. Observe the same and fill in the blanks with suitable answers.
$$(x + y), (x^2 - y^2), (x + y)^2, (x - y), (x^2 - y^2)^2, (x + y)^3, (x - y)^2, --------$$
$$\frac{5}{9}, \frac{10}{28}, \frac{17}{65}, \frac{26}{126}, \frac{37}{217}, ---------$$
$$\left\{\frac{1}{5}, \frac{1}{7}, \frac{1}{9}\right\}, \left\{\frac{1}{11}, \frac{1}{14}, \frac{1}{17}\right\}, \left\{\frac{1}{19}, \frac{1}{23}, -----\right\}$$