Tính:

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Bài 3. Tính:

a) \(\sqrt{x - 3}(\sqrt{x + 2});\)

b) \((\sqrt{x - \sqrt{y}})(\sqrt{x + \sqrt{y}});\)

c) \(\left(\sqrt{\frac{25}{3}} - \sqrt{\frac{49}{3}} + \sqrt{3}\right) \sqrt{3};\)

d) \((1 + \sqrt{3} - \sqrt{5})(1 + \sqrt{3} + \sqrt{5}).\)