3.若点C数线段AB的黄金分割点,且AC>BC,则下列说法正确的有( )
①AB=$\frac{\sqrt{5}+1}{2}$AC;②AC=3-$\frac{3-\sqrt{5}}{2}$AB;③AB:AC=AC:AB;④AC≈0.618AB.
①AB=$\frac{\sqrt{5}+1}{2}$AC;②AC=3-$\frac{3-\sqrt{5}}{2}$AB;③AB:AC=AC:AB;④AC≈0.618AB.
| A. | 1个 | B. | 2个 | C. | 3个 | D. | 4个 |
19.若m为自然数,则多项式x2m+1+3的次数( )
0 309646 309654 309660 309664 309670 309672 309676 309682 309684 309690 309696 309700 309702 309706 309712 309714 309720 309724 309726 309730 309732 309736 309738 309740 309741 309742 309744 309745 309746 309748 309750 309754 309756 309760 309762 309766 309772 309774 309780 309784 309786 309790 309796 309802 309804 309810 309814 309816 309822 309826 309832 309840 366461
| A. | 最低是一次 | B. | 最低是三次 | C. | 不低于二次 | D. | 不高于三次 |