Question

:/ lol help me plsssssss ><

Answer 1

\(1,P=\dfrac{x^3+y^3}{x^2-xy+y^2}\cdot\dfrac{x+y}{x^2-y^2}\\ =\dfrac{\left(x+y\right)\left(x^2-xy+y^2\right)}{x^2-xy+y^2}\cdot\dfrac{x+y}{\left(x+y\right)\left(x-y\right)}\\ =\dfrac{x+y}{x-y}\)

2, Ta có:

\(x=\sqrt{7-4\sqrt{3}}=\sqrt{\left(2-\sqrt{3}\right)^2}=2-\sqrt{3}\\ y=\sqrt{4-2\sqrt{3}}=\sqrt{\left(\sqrt{3}-1\right)^2}=\sqrt{3}-1\\ \Rightarrow P=\dfrac{2-\sqrt{3}+\sqrt{3}-1}{2-\sqrt{3}-\sqrt{3}+1}\\ =\dfrac{1}{3-2\sqrt{3}}=\dfrac{3+2\sqrt{3}}{-3}\)