this is document C. ab\frac{a}{b}ba 3\sqrt{3}3是无理数？ 翻转 y=xy=3x2+5x+2 \begin{aligned} y & = x \\ y & = 3x^2 + 5x + 2 \end{aligned} yy=x=3x2+5x+2 3\sqrt{3}3是无理数？ 翻转
