Answer:
Step-by-step explanation:
4) (a - b)² = a² - 2ab + b²
[tex](5-\sqrt{5})^{2}=5^{2}-2*5*\sqrt{5}+(\sqrt{5})^{2}\\\\ =25-10\sqrt{5}+5\\\\=30-10\sqrt{5}[/tex]
5) Use FOIL method.
[tex](1+\sqrt{2})(3-\sqrt{2})=(1*3)+1*(-\sqrt{2})+\sqrt{2}*3+\sqrt{2}*(-\sqrt{2})\\\\ =3-\sqrt{2}+3\sqrt{2}-2\\\\=3-2-\sqrt{2}+3\sqrt{2}\\\\=1-2\sqrt{2}\\[/tex]
